



GopyiightN". 






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COPYRIGHT DEPOSIT. 



EDUCATIONAL PSYCHOLOGY 

SECOND EDITION 

REVISED AND ENLARGED 



BY 

EDWARD L. THORNDIKE 

PROFESSOR OF EDUCATIONAL PSYCHOLOGY IN TBACHERS COLLEGE 
COLUMBIA UNIVERSITY 



PUBLISHED BY 

©ractj^ra (taiU^, OInlumbia Mniupraita 

NEW YORK 
1910 



-1^ 



0^^ 



^^i^ 



CorYKlGllT, 1903, 1910 

H\ RDWARD L. THORNDIKIC 



TRUSS OF 

FRANK II. UVORY S CO 

ALUANY, N. Y. 



©CI.AJi68683 



PREFACE 



This book is a revision of a book, Educational Psychology, 
which appeared in 1903. Its primary purpose is, as was the case 
with the first edition, to provide students in advanced courses in 
educational psychology with material which they would otherwise 
have to get from lectures at great cost of time. 

The chapter on ' The Influence of Special Training upon More 
General Abilities ' is not included in this edition. It was out of 
place before since it treated facts of mental action in general 
instead of facts of individual mental conditions and their causes. 
It was put in the original book because of the great practical 
importance of the facts concerned. The facts are now widely 
known and are presented conveniently elsewhere. 

This book attempts to apply to a number of educational 
problems the methods of exact science. The problems chosen are 
those of the mental natures of individual men, and the causes of 
their differences. The problems concerned with the nature of 
man as a species, — the general problems of instinct, habit, 
learning, practice, memory, fatigue and the like, — will sometime 
be treated in a separate volume. The two together will, I hope, 
be a serviceable quantitative treatment of educational psychology. 



CONTENTS 



CHAPTER PAGE 

I. Introduction ......... i 

X^ II. 'Th^ Measurement of Individual Differences -.-- „ ... 3 

^Llll. The Influence of Sex ........ 18 

IV. The Influence of Remote Ancestry or Race . 51 

y V. The Influence of Immediate Ancestry or Family ... 69 

VI. The Influence of Maturity ....... 104 

A VII. The Influence of the Environment .114 

VIII. The Nature and Amount of Individual Differences in Single 

Traits ......... 142 

IX. The Relations between the Amounts of Different Traits in the 

Same Individual . . . . . . .171 

X. The Nature and Amount of Individual Differences in Com- 
binations of Traits; Types of Intellect and Character 193 

XI. Extreme Individual Differences; Exceptional Children . 207 

APPENDIX 

I. List of authors and titles referred to specifically in the text . 231 

II. List and descriptions of measurements referred to cursorily 

in the text ......... 236 

III. List and definitions of statistical terms used in the text . 242 



CHAPTER I 

Introduction 

The knowledge of human nature which psychology offers to 
students of educational theory and practice may be roughly 
divided into four parts. A body of general knowledge about 
instincts, habits, memory, attention, interests, reasoning, etc., finds 
place in the ordinary text-books. Detailed descriptions of the 
thoughts, feelings and conduct of certain children at different 
ages are available in the literature of child study. Particular 
facts which bear upon this or that school subject or method of 
teaching may be gleaned from researches upon perception, 
association, practice, fatigue and other topics. Finally there is 
an even more incoherent mass of facts about the differences 
between one human being and another and the respective shares 
which sex, age, ' race ' or remote ancestry, ' family ' or immediate 
ancestry, and the circumstances of life have in the causation of 
these differences. It is the aim of this volume to put this last 
group of facts at the service of students. 

Their significance for educational theory and practice is obvious. 
What we think and what we do about education is certainly 
influenced by our opinions about such matters as individual differ- 
ences in children, inborn traits, heredity, sex differences, the 
specialization of mental abilities, their interrelations, the relation 
between them and physical endowments, normal mental growth, 
its periodicities, and the method of action and relative importance 
of various environmental influences. For instance, schemes for 
individual instruction and for different rates of promotion are 
undertaken largely because of certain beliefs concerning the 
prevalence and amount of differences in mental capacity ; the con- 
duct of at least two classes out of every three is determined in 
great measure by the teachers' faith that mental abilities are so 
little specialized that improvement in any one of them will help 

(1) 



2 Educational Psychology 

all the rest; manual training is often introduced into schools on 
the strength of somebody's confidence that skill in movement is 
intimately connected with efficiency in thinking; the practical 
action with regard to coeducation has been accompanied, and 
doubtless influenced, by arguments about the identity or the 
equality of the minds of men and women ; the American public 
school system rests on a total disregard of hereditary mental differ- 
ences between the classes and the masses ; curricula are planned 
with some speculation concerning mental development as a guide. 
It is thus easy to find cases where educational practice depends 
upon opinions about our group of topics. It is still easier to note 
a similar dependence in the case of educational theory. Abundant 
illustrations will appear in the course of our study of the topics 
themselves. 

Effective description of the facts of individual differences and 
of their causation must be quantitative. The questions are 
questions of amount, or at least become such when carried beyond 
a first survey. "Do boys and girls differ?" is itself a question 
of amount, which soon becomes, " How much do boys and girls 
differ ?" " In what do they differ ?" can be answered only by 
comparing them quantitatively. "Are there distinct types of 
children with respect to imagination?" can be properly answered 
only by measuring children in respect to the various sorts of 
imaginativeness or imagery in question. " What is the value of 
the study of Latin?" means to even the student most averse to 
quantitative thinking, "What changes in human nature are caused 
by it?" But to prove the existence of any change one must 
measure two conditions. 

It is therefore necessary to understand certain elementary facts 
about the means and methods of measuring the facts of individual 
differences and their causation, in order to understand the facts 
themselves. Portions of certain chapters will consequently be 
given up to the essentials of the theory and practice of measuring 
mental conditions, differences, changes and relationships. 



CHAPTER II 

The Measurement of Individual Differences 

Exact knowledge of the nature and amount of individual differ- 
ences in intellect, character and behavior is valuable to educational 
theory and practice for two reasons. The first is the general need 
of knowledge of what human beings are in order to choose the 
best means of changing them for the better — a need which includes 
knowledge of the divergences of individuals from the type of the 
species as a whole, as well as knowledge of that type. Education 
needs knowledge of men as well as of man. The second reason is 
that by a study of the causes of these differences, — the causes 
which make men good and bad, wise and foolish, skillful and 
clumsy, efficient and futile, — education may hope to learn about 
means of making all men more wise, skillful and efficient. The 
causes of the differences between one man and another, as things 
now are, will lead to knowledge of the causes whereby all men 
may be made to differ from their former selves. It is of special 
importance to know what differences amongst men are due to dif- 
ferences in sex, race, immediate ancestry and maturity, which are 
beyond control by ordinary educational endeavors, and what 
differences, on the other hand, are due to training or education 
itself. 

Simple and Compound Differences 

A difference in human nature may be (i) in the amount or 
degree of the same thing* (as 'good — better,' 'quick — slow,' 
^ imaginative — less imaginative — unimaginative ') ; or (2) in the 
presence or absence of different things (as 'John knows Latin; 
James knows German,' or, ' A is imaginative ; B is rational,' or, 
^ C has an artistic temperament ; D has a scientific temperament'). 

*0r what is assumed to be the same thing. 

(3) 



4 Educational Psychology 

The second case commonly reduces to an aggregate of 
differences of the first sort if the statement of dift"erence is made 
adequate. Thus, ' John knows x Latin ; James knows o Latin ; 
James knows 3; German ; John knows German' should properly 
replace the former statement. Similarly we have, * A is imagin- 
ative to 2 extent, B is imaginative to s—zv extent. B is rational 
to V extent; A is rational to v — w extent,' and, 'C has r, y and s 
amounts, respectively, of certain qualities, certain degrees of which 
in combination we call the artistic temperament; D has small or 
possibly zero amounts of these qualities.' A difference in human 
nature then commonly is a difference in the amount of one thing 
or an aggregate of differences each in the amount of one thing. 

But conceivably there may be things which do not vary in 
amount except from zero by a sudden jump to one positive 
condition. The thing would then either be in one constant degree 
or not at all. The literature of psychology and of education 
abounds in cases of difference stated as if the difference were 
that between and k, without k - y^, or ^ - ^^, or k + }ik, etc. 
But such statements are usually due to ignorance or vagueness. 
' John is color blind ; James is not ' cannot really mean that there is 
some one constant degree of color blindness which a man either 
has just in that degree or does not have at all ; for there are 
varying amounts of color blindness. In fact, it is doubtful if there 
are any individual differences in human intellect or character of 
this ' zero to k ' sort. 

When, therefore, it is stated that John and James differ in 
kind, the statement always, or almost always, means nothing more 
than that one of the two individuals possesses a certain amount; 
or degree of something of which the other possesses 0. When 
it is stated that the difference between John and James in one 
thing, say, knowledge, is qualitative whereas their difference in 
another, say, motor skill, is quantitative, the statement always, 
or almost always, means nothing more than that certain sorts of 
knowledge, present in certain amounts in John, are absent in 
James, and vice versa ; whereas, in motor skill, both have percep- 
tible amounts of an identical set of things. 

It is then not only permissible, but more scientific and more 
useful, to think of human individuals as all measured upon the 
same series of scales, each scale being for the amount of some 
one thing, there being scales for every thing in human nature,. 



The Measurement of Individual Differences 5 

and each person being recorded as zero in the case of things not 
appearing in his nature. And the only problem of method which 
need concern us in this chapter is the problem of the nature and 
use of a scale for measuring different amounts or degrees of the 
same trait in different human beings. 

Units and Scales for Measuring Mental Differences 

The facts of importance about scales for mental and moral 
traits can be best stated in connection with some concrete illus- 
trations. 

Consider the facts given in Table I concerning individuals 
A, B and C, with reference to these questions : — 

1. What are the differences between A and B, A and C, 

and B and C in each of the traits ? 

2. How many times as great is the difference between A and B 

in trait I as that between B and C in trait I ? How many 
times as great is the difference between B and C in trait 
n as that between A and C in trait H, etc., etc. 

What the difference is between A and B can be definitely deter- 
mined in the case of stature (I), reaction-time (H), error in 
drawing a line (HI), and age (XH) ; but all that one learns 
about the differences in the case of ability in history (VH) and 
interest in music (XI) is that one difference is that between 
excellent and good on the arbitrary scale of some school and 
that the other is that between little and moderate, in the mind 
of some observer. The measures of I, H, UI and XH are by 
objective or impersonal scales, that is, scales the identification and 
similar use of which are possible for any competent observer. 
The measures of VH and XI are by subjective or personal scales, 
which another observer could not identify* or use in the way in 
which the person giving the marks used them. Moreover, what- 
ever the scales in VII and XI really are, they are certainly very 
coarse ; a wide range of difference is expressed in them by a few 
steps or marks or values. In short, any competent thinker knows 
exactly what is meant by 160 cm. and by 160 cm. — 140 cm., 

*If, for example, the reader had heard the oral work and seen the 
written work which in combination mean good in the school whence 
A and B came, he would not know that they did mean good. 



Educational Psychology 



TABLE I. 
Measurements op Three Individuals, A, B, and C 

ABC 

I. Stature 160 cm. 140 cm. 130 cm. 

II. Simple reaction-time to sound 175 sec. .125 sec. .150 sec. 

III. Average error in drawing a line to 

equal a 100 mm. line 3.2 mm. 2.8 mm. 2.2 mm. 

IV. Number of words (of a list of 12, 

heard at a rate of i per second) 
remembered long enough to write 
them immediately after the last 
word was read 6 words 9 words 7 words 

V. Number of examples in addition 
(each of 10 numbers, repeating no 
number in any one example, taken 
at random from the numbers 10 
to 99) done correctly in 8 minutes 14 12 18 

VI. Quality, or merit, or goodness of 

handwriting See Fig. i See Fig. 2 See Fig. 3 

VII. School marks in history Ex. Good Poor 

VIII. School marks in spelling 82 62 93 

IX. Efficiency in perception ; the number 
of A's marked in 60 seconds on a 
sheet containing 100 A's mixed 

with 400 other capital letters ... . 48 A's 60 A's 82 A's 
X. Criminality: number of times con- 
victed of a penal offense 010 

XI. Degree of interest in music little moderate a great deal 

XII. Age in days 5080 d. 6150 d. 5615 d. 

whereas he cannot be sure what is meant by excellent, or by the 
difference between excellent and good. 

Concerning the other measurements the following statements 
are roughly true : — 

A, B and C are measured objectively in the quality of hand- 
writing. We know what is meant by the difference between 
A and B. It is just the difference between the qualities of the 
two samples presented. But they are not measured conveniently ; 
the differences are not referred to any commonly known scale. 

The measurement in addition is nearly objective. If the 
conditions of the test are defined by a statement of how the 
examples were presented (what type they were printed in, how 
they were arranged, etc.), how the answers were given, at what 



The Measurement of Individual Differences 




_g 

•n 

•a 
n 

ni 

W 
pq 



^ 



.<< 



^ "3 




8 Educational Psychology 

time, under what distractions, with what incentives, etc., they 
were done, and the Hke, they become still more fully objective. 

In the case of memory, not only the conditions of the test, as 
in addition, but also the exact words used need to be specified. A 
differed from B by writing down three less words of a certain 
list. The list needs to be known if all competent observers are 
to think of the same thing by three zvords. 

The measure of criminality is inferior to the measurement of 
stature or age by using an ambiguous unit {convicted of a penal 
oifense) and also by measuring only very coarse diflferences. 
A and C are not differentiated by the measures, though A might 
just fall short of crime and C be a very healthy-minded and 
kind-hearted boy. 

The measurement of ability in spelling might turn out to be, 
were the conditions of the test and the system, of scoring results 
in it known, as objective as that in addition, or, on the other 
hand, may be only a record of the opinion of some teacher that 
A was a good deal better than B and that C was somewhat 
above A. As the record stands the A — B = 20 may mean no 
more than 'A is good; B is unsatisfactory,' or 'A is soniezvhat 
better than B in my opinion.' 

The values ~^ > A — C ^"^ p_p ^^^ determinable m the 

case of I, II, III and XII of Table I. In stature A — B = 20 cm., 

A B 

A — C = 30 cm. and -r p^ = .667. When one says that A 

differs from C in stature one and a half times as much as from B, 
any competent person knows exactly what is meant. For VII 

, A — B Excellent — Good ,. . 

on the contrarv we have -r ^ = zz^ n — ;- which 

A — C Excellent — Poor, 

may be a true, but remains a mystical, answer, until excellent, good 

and poor are defined on some scale. 

In the case of the memory of words (A = 6, -B = 9, C = y) 

B — A J B — C 

Q A = 3 s"*i p ^ = 2 , if to remember any one word = to 

remember any other one zvord. Suppose, however, that the series 
of words was : * career, dilatory, opium, never, soap, numbers, 
add, subtract, one, two, three, four,' and that A remembered the 
last 6, C the last 7, and B these and the first two. It would 



The Measurement of Individual Differences . g 

be very risky to assume that the difference between A and B (re- 
membering career, dilatory and numbers) was only three times 
the difference between A and C (remembering numbers). And 
it would be almost certain that a difference of lo — 4 in the test 
would be really more than twice as great as a difference of 7 — 4. 
Under the circumstances numbers, add and subtract are probably 
much easier to remember than career, dilatory and opium. 

In the case of centimeters or seconds every competent person 
knows not only what fact is meant by any given number of the 
units, but also that any one unit is equal to any other one, any two 
to any other two, and so on. In the case of words remembered, 
units called by the same name may not be really equal. 

In the case of the addition, one example differed from another 
in difficulty only by chance and only slightly ; for when 10 two- 
place numbers are picked by chance and arranged in a chance 
order, the chances are enormously against getting any very easy 
examples like (a) or any very hard examples like (b). 

(a) (b) 

25 89 

35 95 

30 58 

40 67 

60 79 



The chances are still more against getting two or three examples 
in succession that are on the average more than a trifle harder 
than any other succession of two or three. Reliance upon the truth 

of 7:;^ — = — - would, however, be safer if 10, 20, 30, etc , and 

C — B 6 

II, 21, 31, etc., had been excluded from the numbers used in 
the tests. 

In the case of merit of handwriting, the differences between 
A and B, B and C, and A and C do not even pretend to be put 
in terms so as to allow comparison. As the records stand, 
any one must get the differences transposed into terms of some 

^ g 

unit before he can calculate at all. Since the measures 

A — C 

of A, B and C are objective, this can be done. If, for example. 



lo Educational Psychology 

the measurer could show that the difference between A and C 
was approximately five-twelfths of the difference between two 
standard samples accessible to all competent persons, and that the 
difference between A and B was approximately two-twelfths of 
the difference between the same two standard samples, he could 

then regard -r — ^ as, of course, ^— p or -, k being the difference 

between the two standard samples. As a matter of fact the 
difference between the sample of Fig. i (p. 7) and that of 
Fig. 3 (p. 7) is in the combined opinion of some hundred judges 
just about two and one-half times as great as the difference 
between the sample of Fig. i and that of Fig. 2 (p. 7). 

The sum and substance of the last four pages is that a measure- 
ment of human nature to be useful for our purpose must identify 
the amount in question for any competent thinker, just as a 
useful description must identify the object in question. To do 
this it must be objective, that is, free from individual caprice, 
so that any competent person making the same measurement 
would get the same result.* 

It should also, if possible, so state the amount in question that 
other amounts of the same thing may be compared with it as 
so much greater or less, permitting differences between the 
amounts to be expressed in ratios. In still briefer terms, the 
measurements should be at defined points on an objective scale, 
the distances of these points one from another being also defined. 

The reason for the elaborate introduction to and illustrations 
of this obvious principle is that in its application to particular 

*Not, of course, exactly the same. There is a personal equation in 

even the most objective measures, such as the length of this line . 

If they measured it to thousandths of a millimeter, competent observers 
would not get the same result, except by chance. Nor would the same 
observer in several independent measurements. The ultimate distinction 
between objective and subjective is simply that in the former sort of 
measurements competent observers use very nearly the same criteria and, 
tho independent, agree very closely, whereas in the latter they use very 
different criteria and, if independent, agree only roughly. The reader may 
safely postpone any subtle or thoroughgoing treatment of the distinction 
until he can study the theory of mental measurements in detail. For the 
purposes of this book, objective measures may be defined as measures 
which competent observers could repeat and verify or reject, and subjective 
measures as measures which they could not so repeat and verify. 



The Measurement of Individual Differences ii 

problems in the study of educational psychology it has not been 
obvious to even the writers of treatises and investigators of 
original data, much less to the rank and file of students of 
psychology or of education. On the contrary this entire chapter 
would not suffice to list and barely describe the quantitative con- 
clusions that have been drawn from subjective opinions or from 
the acceptance as equal of units which happened to be called by 
the same name. 

The reason for contrasting physical and mental measurements, 
to the apparent disrepute of the latter, is not that I wish to dis- 
courage the reader from trusting, or from making, measurements 
of any feature whatever of intellect or character. It is to be 
hoped, however, that he will be effectually discouraged from 
trusting measurements which do not deserve trust. The lesson 
to be drawn from the contrast is that a measurement can rightly 
be trusted or rejected or criticized or, indeed, understood, only 
if the concrete reality which it describes is known. Any numerical 
statement has meaning only in reference to a concrete scale and 
its units. 

The Variability of a Mental Measurement 

One cause of improper distrust of measurements of intellect 
and character is so common that it demands special treatment. 
This is the variability of the same measurement of apparently 
the same fact.' For instance, individual A was tested by hearing 
a series of 12 letters read at a rate of 2 per second, he being 
required to write down as many as he could remember in theii: 
proper order as soon as the reading was finished. His score 
was 4 correct in one trial and 10 correct in another, the two 
letter-series being, for people in general, of equal difficulty. What 
assurance, it may be said, can be felt in a measurement 
of now 4 and now 10 for the same fact? The defense is that 
it is not the same fact. To measure A's memory for series of 
letters is not to measure one constant thing, but a very variable 
thing. A, as regards taking in and holding a series of letters, 
is not the same from moment to moment. What is measured in 
one trial is a sample of A's varying status in respect to this 
ability. His first score in the measurement in question was 4. 
This measurement is, so far, so good ; it is better to believe that 



12 Educational Psychology 

A's ability in that test is 4 than to guess at it. In a second test 
the score was 10. 

To say that A's ability is 4 or 10 or averages 7 is better than 
to have taken the 4 as a measure. But further trials give 
(including these two) 



I record of 4 


letters correct 


4 records 


" 5 






4 " 


" 6 






7 " 


" 7 






13 " 


" 8 






3 " 


"9 






4 " 


"10 







From all these scores we get, as an average, 7.44 letters 
correctly written; as the most common record (the so-called 
Mode), 8 letters correctly written. Since a record of 4 letters 
correctly written means, perhaps, 4^/^ letters remembered, one 
of 5 letters correctly written, 55^ letters remembered and so on, 
we should perhaps call A's average memory letters 7.94 and his 
mode or most frequent performance 8.5.* 

Now the trustworthiness of any one of these is 6 times as great 
as that of the first single score 4.t But we can not be sure 
that the average of the 36 measurements is identical with A's 
true average ability. In fact we can be almost sure that it is 
not. Seventy-two measurements might give, and almost certainly 
would give, a slightly different average. True average ability 
in the case of variable measurements means the measure we 
would get as an average from an infinite number of measure- 
ments. Only by chance will the result from any finite number 
of measurements be identical with it. All our measures represent 

*If an individual writes 7 letters correctly, but does not write an eighth, 
it means that he remembered at least 7 and not 8. The measurement is 
comparable to one of length in which the observer notes that a stick is 
over 62 inches, and is not 63 inches, long. And just as, in the long run, 
sticks 62 inches or over but not 63 inches or over will average 62Y2 inches, 
so the person remembering on many occasions at least 7 but not 8 letters 
will average 7V2 letters. Some of his records of 7 mean 7 letters remem- 
bered and one more letter almost, but not quite, remembered. 

fit is found in variable measurements of the ordinary sort that the 
reliability of an average increases as the square root of the number of 
measurements taken. 



The Measurement of Individual Differences 



15 



approximations, but the greater the number of measures the closer 
the approximation will be. 

The series of measures above is our knowledge of A's ability. 
We can see the fact more clearly by expressing it in space rather 
than in figures. If we let each quarter inch along a horizontal 
line stand for one letter correctly written, and each eighth of 
an inch of height above it stand for one manifestation by A 
of the ability designated by that place, we have Fig. 4, by which 
one can see at a glance A's ability, its variability and his general 
tendency to keep nearer 8 than any other one ability. 



4 5 6 7 8 9 10 

Fig. 4. The ability of individual 



5 6 7 8 9 

Fig. 5. The ability of individual 
A in memory of letters. B in memory of letters. 

If we must for any reason abbreviate our description of A's 
ability we may best take two measures, one of the ability about 
which his various scores center most closely and the other of the 
closeness of his grouping. We may term these the central tendency 
and the variability. For the former the average or median* or 
mode may be used, for the latter the average of the differences 
between the individual records and their central tendency 

*The Median has two meanings : the point on the scale above and below 
which equal per cents of the individual scores lie, and the mid measure, 

that is, the — — — th measure, counting in from either extreme, where 
2 

« = the total number of measures. These two definitions lead to sub- 
stantially the same results, and for present purposes the reader may adopt 
either one. Indeed it will do no harm if he can see no difference between 
the two. 



14 Educational Psychology 

(Average Deviation or A.D.), or any one of a number of measures 
of the closeness of clustering of the individual records about their 
central tendency. 

Let us suppose that, with the same test, individual B showed 
the following ability: 

2 records of 5 correct. 

II " 7 

17 " 8 

3 " 9 " 

This is shown graphically in Fig. 5. The average, median 
and mode would be closely the same as for A, but the variability of 
the measures would be less. The limits for A were 4 — 10. For 
B they are 5 — 9. The average difference of the individual 
measure from the mode for A was 1.17. For B it is 0.7. B's 
ability has the sam,e central tendency as A's, but B is a more 
constant performer. 

It is obvious that an average from a set of measurements like 
the second is less likely to deviate from the true status than an 
average from a set like the first. And in general the less the 
variability of the single measures the greater the reliability of the 
result inferred from them. 

In the case of A's memory we should say, using formulae the 
derivation of which need not be described here: From what 
knowledge we have, the most likely true average number of letters 
correctly written for A is 7.44; the chances are 

1 to I that the true average does not differ from 7.44 letters correctly 

written by more than .171 

2 to I that the true average does not differ from 7.44 letters correctly 

written by more than .245 

3 to I that the true average does not differ from 7.44 letters correctly 

written by more than .291 
99 to I that the true average does not differ from 7.44 letters correctly 
written by more than .651 
999 to I that the true average does not differ from 7.44 letters correctly 
written by more than .835 

The variability of mental measurements thus gives no reason 
to distrust them, but, on the contrary, gives a means of knowing 
just how trustworthy they are. 



The Measurement of Individual Differences 



15 



Methods of Reporting Individual Differences Within Large 

Groups 

Suppose now that the average abiHty in remembering letters 
in such a test as that described had been determined for every 
human being six years old or older. From such records the 
difference of any individual from any other could be computed, 
but only by hunting out the records of the two individuals. The 
frequency of any given degree of difference could be found a 
very simple summary of such records, such as appears in Table 2. 



TABLE 2 

Supposed Distribution of Average Ability to Remember Letters in 
THE Case of Human Individuals Six Years Old or Older 



An average of o letters was remembered by 

1 letter " 

2 letters " 

3 " " 
4 

6 " 

<< " 

8 

9 " " 

ID " 

11 " 

12 " 

13 " 

14 " 

15 " 

16 " 

17 " 

18 " 

19 " 

20 " 



o individuals 

2,000,000 

30,000,000 

60,000,000 

190,000,000 

280,000,000 

360,000,000 

310,000,000 

190,000,000 

40,000,000 

6,000,000 

400,000 

100,000 

40,000 

20,000 

4,000 

500 

100 

5 
o 
o 



A difference of 17 occurs only 10,000,00 times, between 
each of the individuals of ability 18 and each of the 2,000,000 
of ability i. A difference of 16 occurs 350,000,000 times 
(5 times 30,000,000+100 times 2,000,000). A difference of 15 
occurs 4,300,000,000 times (^ times 60,000,000+100 times 
3,000,000 -J- 500 times 2,000,000) . 

A distribution or table of the frequencies of the abilities of 



i6 



Educational Psychology 



individuals is then a convenient means of presenting the facts 
from which the frequencies of the different differences amongst 
them may be calculated. It serves many other purposes as well, 
and so is commonly used in reporting the results of the measure- 
ment of any one trait in a number of individuals. The main 
features of such a table can be seen at once in their relations 
one to another if it is presented in graphic form. Thus 
Table 2 becomes Fig. 6, by letting the amounts of the trait be 
represented along a horizontal line and the number of persons 
possessing each amount be represented by the heights of a column 



3S — 
30- 

iO- 



1 2 8 4 5 6 7 8 9 10 11 12 13 



18 



Fig. 6. Relative frequencies of the different abilities in remembering 
letters of human individuals six years old or older. The horizontal scale is 
for the average number of words remembered. The vertical scale is for the 
number of individuals, 10,000,000 being the unit. 



erected at the place on the scale denoting that amount. Such a 
graphic representation is called a surface of frequency or a surface 
of distribution; the line which, with the base — or scale — line, 
encloses this surface is called a frequency curve or distribution 
curve. 

No one has measured all human beings or even a small but 
fair sampling of all human beings in even a single mental trait. 
Nor, as we shall see, would that be a very useful undertaking. 
If there were such measurements, — if, for example, Table 2 and 
Fig. 6 represented actual facts, — they would emphasize the 
problem, which should be emphatic enough without them, of 
accounting for every difference existing. They would also make 



The Measurement of Individual Differences 1 7 

it easier to see, what is already clear enough, that accounting for 
every difference is the same as accounting for each person's 
position on the scale, — each person's amount of the trait. It is 
this problem of the causes of individual differences or the causes 
of each individual's amount of each trait that is to occupy our 
attention in the next five chapters. 



CHAPTER III 
The Influence of Sex 

Preliminary Cautions 

By way of preface to an account of sex differences it is well 
to note that their existence does not necessarily imply in any 
case the advisability of differences in school and home training, 
and, on the other hand, that even if the mental make-up of the 
sexes were identical it might still be wisest to educate them 
differently. It is true that a difference of two groups in a mental 
trait will theoretically involve differences in treatment, but prac- 
tical considerations apart from that of developing the highest 
efficiency in that trait may outweigh the advantages of the differ- 
ential treatment. For instance, consumptives theoretically need a 
different mode of life from people with healthy lungs, but it 
might in some cases be wiser to leave a consumptive to his 
ordinary habits rather than to cause in him consciousness of his 
disease and worry concerning it. On the other hand, two boys 
might be identical in mental structure, yet their education might 
best be very different if we wished to make one of them a 
chemist and the other a psychologist. 

Let us note in the second place that the existence of differences 
need not imply the need of different training, because those 
very differences may have been due to the different training 
actually received and might never have appeared had training 
been alike in the two classes. It is folly to argue from any 
mental condition in an individual or class without ascertaining 
whether it is due to original nature or to training. 

The chapter should properly be devoted exclusively to the 
differences necessarily produced by sex. Those produced by 
virtue of the adventitiously different training which boy and girl 
undergo belong in chapter VII. So far as may be, such a 

(i8) 



The Influence of Sex 19 

separation of differences due to sex-nature from those due to 
our traditional treatment of the sexes is in fact made. But in 
many cases where the amount of the difference that is to be 
credited to training- is doubtful, the difference will be described 
in the present chapter, the discount to be made being left to the 
reader's judgment. 

A further caution is necessary before this description and 
incomplete analysis begins. It is not to confuse differences in 
behavior, achievement and mental activities indirectly caused by 
physical traits with such differences directly caused by mental 
traits. Lack of muscular strength and the phenomena intimately 
associated with bearing children may serve as samples of such 
physical traits. Even if women possessed mental capacities for 
business identical with those of men, they still might not in active 
work do as much. 

In the fourth place the fallacy of unfair selection must not be 
forgotten in our comparisons of men and women. For instance, 
any inference from a comparison of yoimg men and women in 
college or of working women with men in the same profession is 
untrustworthy. College women and college men are two classes 
selected by different agencies. The intellectual impulse has been 
relatively a more powerful agent in sending girls to college, 
while convention and the demand for a pleasant social and 
athletic life have acted more powerfully on boys. In the case 
of an industry, say laundering, women are selected by relative 
ignorance, strength, widowhood, drunken husbands, etc., while 
the men are selected largely by Chinese birth. Let not the 
bizarre nature of this particular illustration blind us to the fact 
that women and men physicians, lawyers, stenographers, teachers 
or government clerks represent different samplings of the two 
sexes. It is possible theoretically to make a discount for the 
differential influence of selective agencies and thus permit a fair 
comparison, but the amount of the discount is very hard to 
determine. 

The investigator of the direct share of sex in the production 
of mental differences would like to compare individuals alike in 
age, race, immediate ancestry and training, different in sex alone. 
The nearest approach that he can make to this crucial comparison 
is to compare a brother with his twin sister in the case of families 



v/ 



20 Educational Psychology 

where the treatment of the two is most ahke.* What he has 
done is to take such measurements as he can get, of boys and 
girls or men and women as nearly alike in age and race and 
training as practical exigencies allow, and to measure enough 
individuals to make the average immediate ancestry of the one 
group nearly like that of the other. 

A Sample Study of the Influence of Sex 

I shall report as a sample of such studies, that of Dr. Thompson. 
[Thompson, H. B., '03] This report will be followed by a state- 
ment of present knowledge concerning sex differences, first in 
intellectual or semi-intellectual abilities, including sensory and 
motor abilities, and then in those interests, tendencies and propen- 
sities which constitute what we roughly call character and tem- 
perament. 

Dr. Thompson describes the essential arrangements made by 
her to secure a just measurement of sex differences, as follows : — 
['03 ; pp. 2-6, passim] 

" In order to make a trustworthy investigation of the varia- 
tions due to sex alone, therefore, it is essential to secure as 
material for experimentation, individuals of both sexes who are 
near the same age, who have the same social status, and who 
have been subjected to like training and social surroundings. The 
complete fulfilment of these conditions, even in the most demo- 
cratic community, is impossible. The social atmosphere of the 
sexes is different from the earliest childhood to maturity. 
Probably the nearest approach among adults to the ideal require- 
ment is afforded by the undergraduate students of a coeducational 
university. For most of them the obtaining of an education has 
been the one serious business of life. They have had at least 
the similarity of training and surroundings incident to school life. 

*I have made this comparison in the case of ten pairs of twins from 
9 to 15 years old, in simple but fairly precise tests of efficiency in perceiving 
small details (A test, a-t, r-e, and misspelled word tests) and of 
efficiency in controlled associations of ideas (opposites test, addition and 
multiplication). The difference between boy and girl of a pair of twins 
varies greatly, but the general result is an absence of difference, the boys 
doing worse by i per cent in the former and better by 2 per cent in the 
latter tests. This general result might change if ten thousand instead of 
ten pairs were studied, but the chances are over 9 out of 10 that there 
would not be a difference of 15 per cent in favor of either sex. 



The Influence of Sex 21 

Most of those in a western university have received their education 
in coeducational schools. 

The individuals who furnished the basis for the present study 
were students of the University of Chicago. They were all juniors, 
seniors, or students in the first year of their graduate work. The 
original intention was to limit the ages to the period from 
twenty to twenty-five years. Owing to the difficulty of obtaining 
a sufficient number of subjects within these limits, a few 
individuals of nineteen years, and a few over twenty-five were 
admitted. The subjects were obtained by requesting members 
of the classes in introductory psychology and ethics to serve. 
They were told nothing about the object of the tests except that 
they were for the purpose of determining psychological norms. 

The series of questions on age, health and nationality, 

shows that in all these respects the m.en and women tested were 
closely comparable 

The series of tests employed in this investigation required 
from fifteen to twenty hours of time from each subject. The 
hours were arranged from one sitting to the next according to 
the convenience of the subject. It was not possible to have the 
hours for any one test constant for all subjects, since the schedules 
varied so widely. No attempt was made to keep the order of 
experiments rigidly the same for all. Convenience and economy 
of time necessarily determined the order to a great extent. In 
general, however, the simple sensory and motor tests were given 
in the early part of the series, and the intellectual tests in the 
latter part. The questions on personality usually came last. 
The taste and smell experiments had to be scattered through 
most of the periods, since only a few at a time could be performed 
without fatigue. The entire series was applied to fifty subjects, 
twenty-five men and twenty-five women. 

The experiments fell into seven groups, dealing respectively 
with motor ability, skin and muscle senses, taste and smell, 
hearing, vision, intellectual faculties, and affective processes. . . . 

A few words in general on the methods employed may not 
be out of place, in spite of the fact that each is described in 
full in connection with the test. The guiding principle in selecting 
the method was the desire to make the directions to the subject 
as clear and simple as possible and at the same time secure the 
greatest possible accuracy of result." 



22 



Educational Psychology 



The following quotations give an idea of details of method in 
the case of two of the tests of " intellectual faculties " : — 
[Thompson, '03, pp. 111-114] 

Test I for Ingenuity 

" Fifteen matches were laid on the table in such a way that 
they formed five squares in the relative position shown in Fig. 7. 
The subject was then asked if he had ever seen the figure before 
or knew its purpose. One of the fifty — a woman — had seen it 
before, but had forgotten its purpose. She found the solution in 
ten seconds, but since she was doubtless assisted by her previous 
acquaintance with the figure, her record is not included in the 
curve. The others, upon stating that they had no previous 



Fig. 7. 

knowledge of the figure or its purpose, were told that the problem 
was to remove three matches from it in such a way that three 
perfect squares only remained ; in other words, to remove three 
matches in such a way that every match remaining on the table 
after the three were removed should be a part of a perfect square. 
No rearranging of the remaining matches was allowed. The 
subjects were all given exactly the same directions, and were 
left entirely free to use any method they chose. Removing 
matches on trial was permitted. Time was counted from the 

moment the conditions were understood 

The second ingenuity test was designed to call a pure process 
of reasoning into play. It consisted of a puzzling mathematical 
problem, perfectly simple in the computations involved but 
demanding a somewhat complicated process of reasoning for its 
solution — a problem in which it was easy to become confused 
unless all the factors were sharply separated and clearly grasped. 
The problem was handed written to the subject. He was told 
that it involved no difficult computations. The process was 



The Influence of Sex 23 



g + 
S • 

H + 
3 «• 

I II 1 1 n i l 1 1 1 1 1 1 r 

Oin45S7?ilO 15 20 2J id 35 

6 



3 • + + • • 

2 + + 

r' l I I I I I I I I I 1 1 1 1 I 1 1 f — 

02 U glOI2l1IUno iS 30 35 10 IS 50 55 * 

i 

7 

6 

5 • • 

3 . + 

2 + * + + 

]+ + + + • + -• 

I 1 1 1 1 1 r 1 1 1 1 1 1 1 I 

5 10 15 20 2S 30 35 10 W 50 55 60 ^5' 15 P 

Figs. 8, 9 and 10. Comparison of men and women in respect to three tests 

of ingenuity. The horizontal scales are for the time ( in minutes ) taken to 

solve the problem. The vertical scales are for the number of individuals. 

The height of a dot represents the number of men whose times fell within the 

division of the scale above whose right limit the dot stands. The height of 

a cross has the same meaning, but for women. Thus ( in the middle diagram ) 

4 men and i woman took from o to 2 minutes, 3 men and i woman from 2 

to 4 minutes, 3 women and i man from 4 to 6 minutes, in the second test in 

ingenuity. 

Fig. 8 ( at the top ) records the results in the first test of ingenuity. 
Fig. 9 (in the middle ) " " " " " second test of ingenuity. 
Fig. 10 (at the bottom ) " " " " " third test of ingenuity. 



24 Educational Psychology 

timed from the moment the problem had been read through. A 
failure was recorded only in cases in which the subject had 
worked from forty-five minutes to an hour, and was completely 
hopeless of getting any solution. The problem was the following : 
' A man swimming in a river finds that he can swim three times 
as fast down stream as up stream. The river flows at the rate 
of a mile an hour. Find his rate of swimming in still water.' 
Any solution which could he explained was accepted. A mere 
stumbling upon the correct answer was not called a solution." 

The third problem was to place eight counters on a checker- 
board of 64 squares so that no two counters were on the same 
horizontal, vertical or diagonal row of squares. 

The results of these three tests are shown by Dr. Thompson in 
the curves reproduced in Figures 8, 9 and 10. 

Means of Measuring the Dirferences Between Two Groups 

These distribution curves show fully the differences between 
the men and the women, but they do not show them very con- 
veniently. For convenience in comparing the difference in, say, 
the second of these tests of ingenuity with the difference in the 
third or in comparing the difference in any one of them with 
the difference in memory or accuracy of movement or rate of 
association, the difference in any one trait should be represented 
by some one amount. 

There are two ways of representing the difference between two 
groups by one amount. The first is by stating the difference 
between the two central tendencies. Thus in the second test 
above the two tables of frequency are as in Table 3. The average 
is not here a suitable measure of the central tendency since 
' failed ' cannot be given a numerical value.* There is no clear 
mode for either men or women. The median is however a useful 
measure here. The median, in the sense of the point on the 
scale which will have half of the men's records above it and half 
below, is somewhere between 12 minutes and 14 minutes. Just 
where it is for these 25 men cannot be stated since we do not 
know the exact records of the three men who took from 12 to 14 
minutes. It would be at the point of the quickest of these three 
men. The most probable place for him is from 12 to I2f 

*Also for other reasons. 



The Influence of Sex 



25 



TABLE 3 

Comparison of Men and Women in Ingenuity — Second Test 
Frequencies of Different Times Taken in Solving the Problem 



o to 2 minutes was required by 



2 

4 

6 

8 

10 

12 

14 
16 
18 
20 

25 
30 

35 
40 

45 
50 



4 

6 

8 

10 

12 

14 
16 
18 
20 

25 
30 

35 
40 

45 
50 
55 



en 


Women 


4 and I 


3 


' I 


I ' 


3 


' 


3 


3 


' I 


I 





3 





' 


4 


' 


' 


' 


' 2 


I ' 


' I 


I ' 


' 2 


I 


' I 


' 


' I 





' 


' 


' 


I ' 


' 


6 


5 



Failed in 45 to 60 minutes 

The median man required 12^ minutes; the median woman, i^H 
minutes. 

minutes. The midpoint of this place is 12^ minutes. The 
median for women is the slowest of the 4 records in the 14-16 
minute group. The most probable point for this is 15I minutes. 
The median man is thus 3xV minutes quicker than the median 
woman in this test and requires only 8 tenths as long as she. In 
the third test of ingenuity the median man is the slowest one of 
the three taking from 20 to 25 minutes, while the median woman is 
the quicker one of the two taking from 60 to 65 minutes. The 
most probable points for them are respectively 24.17 and 61.25. The 
median man is thus 37.08 minutes quicker than the median woman 
in test 3 and requires only 4 tenths as long. 

The second method of representing the difference between two 
groups by one amount is by stating the per cent of one group 
that reaches or exceeds a given record made by some one of 
the other group. Thus in the second test of ingenuity 60 per cent 
of men reach or exceed (that is, are quicker than) 16 minutes, 
which is reached or exceeded by 52% of women. 48% of men 
reach or exceed 12 minutes, which is reached or exceeded by 
36% of women. The particular comparison of this sort of 



26 Educational Psychology 

most service is the per cent of group i reaching or exceeding, 
the median of group 2. In test 2, 60% of men reach or exceed 
the mecHan for women. In the case of the third test 69% of 
men reach or exceed the median for women. 

The great advantage gained by comparing groups by the per 
cent of one group reaching or cxceecUng the point on the scale 
that is reached or exceeded by a given per cent of the other 
group is that rcsuhs are mutually comparable whatever the traits 
may be. In place of a list of differences now in time taken, now 
in amount done, now in quality of this product, now in the amount 
of that error made, etc., etc., the second method gives a simple 
list of per cents of men who reach ihe median for women. Another 
advantage lies in the fact that this percentile comparison reminds 
one constantly of the overlapping of the two groups, when such 
exists. 

This second method should, therefore, be used in the statement 
of sex dilTerences, and may be used exclusively for very small 
dil'ferences and differences measured in ambiguous units such as 
school and college marks. 

Unfortunately, of the investigators who have made mental 
measurements of men ami women, few have realized the need of 
presenting the distribution of the trait in question for each sex, 
and still fewer have calculated the per cent of one group passing 
the point passed by half (or by any other assigned per cent) of 
the other group. Many of the measurements of sex differences 
thus remain incommensurate with the rest and are incapable of 
inclusion in an exact general estimate. 

Dr. Thompson does give the entire distributions so that we can 
summarize the essential features of her results in the following 
table (Table 4) :— 

The Results of Measurements of Sex Differences 

In examining Table 4 and similar results it will be Mistruc- 
tive to have clearly in mind the significance of different per 
cents of one sex reaching or exceeding the median of the other 
sex. 50 means of course that the central tendencies of the two 
sexes are identical. 

45 o^ 55 nicans the amount of dift'erence shown in Fig. 11. 

40 or 60 means the amount of dift'erence shown in Fig. 12. 

25 or 75 means the amount of difference shown in Fig. 13. 



The Influence of Sex 27 

TABLE 4. 
Differences between Young Men and Young Women in Various 

Mental, Processes. 

In the case of 50 students in the University of Chicago of approximately 
equal age and academic status the per cent of men reaching or exceeding 
the median of the women is as follows: — 

In reaction time 68 • 

Rate of tapping with finger for first 20 seconds 81 

" " ' last 20 " of 120* 81 

Sorting cards by color ; speed 14 

" " " " accuracy 44 

Accuracy in thrust from the shoulder at a target approx. 60 

" " free arm drawing of a line within an angle 72 

Lowness of threshold for sensations of impact 43 

" pain 46 

" taste (the presence of a taste) . . 34 
(recognition of it as sweet, 

salt, sour or bitter) 34 

presence and recognition of 

sweet and salt 45 

of sour and bitter 22 

" smell (cloves and violet) pres- 
ence 43 

recognition 41 

* light 62 

Range of sensitivity to pitch; upper limit 52 

" " " " " lower limit 50 

Delicacy of discrimination of differences in pressure 47 

lifted weights 66 

" (points on the forearm) 

crosswise 43 

lengthwise 18 

" area on the skin 61 

" " " " temperature (at 30 C.) 53 

(at 5 C.) 36 

(at 45 C.) 52 

" " " taste (sweet 64, salt 35, sour 

67, bitter 65) 58 

" " " " " " smell (cloves 48, violet 51). 50 

" " " " " " pitch 44 

" brightness 78 

" " " " " " color (as in tests for color- 
blindness) 24 

" area by the eye 56 

*Six women of the twenty-five could not continue so long as the most 
easily fatigued man. Two men and two women stopped after 100 seconds. 
The others tapped for 120 seconds. 



28 



Educational Psychology 



Memory of nonsense syllables; rate of learning, auditory 32 

" " " " " " " visual 46 

Retentiveness after one week ; auditory 5 ^ 

visual 43 

{Quickness in solving ingenuity test i 46 

" " " 2 60 

" " " 2 69 

" 4 68 

" " " e 72 

General information 5° 

Information about English literature 31 

" " physics 76 



-...^a^rr^: 




Fig. II. The amount of difiference between two groups when the per 
cent of one group reaching ; or exceeding the median of the other group is 
45 or 55. 




Fig. 12. The amount of difference between two groups when the per 
cent of one group reaching or exceeding the median of the other group is 
40 or 60. 




Fig. 13. The amount of difference between two groups when the per 
cent of one group reaching or exceeding the median of the other group is 
25 or 75. 



The Influence of Sex 



29 







*j 

u 

o 

a 

a 

bo 

,g 
•S 

(L) 
<U 
U 

<u 
o 

bo 

a 
y 

ii 

cu 

3 . 
O O 

bo M 

o o 



c 

u o 
a. bJ5 
V 

a 



tn 
O 

&, 

y 

c 

. (U 

y 
it! 



y 
y 







6 



1 



A per cent of 100 is ambiguous, meaning anything from the 
amount of difference shown in Fig. 14 to an amount as great 
as or greater than that shown in Fig. 15. So also a per cent of o 



30 Educational Psychology 

is ambiguous, meaning possibly a difference as little as that of 
Fig. 14 (reversed), and possibly a difference as great as or 
greater than that of Fig. 15 (reversed). 

As a matter of fact there is no intellectual ability among those 
so far measured in which the percentage of males reaching the 
median for females is as low as o or as high as 100. The groups 
always over-lap to the extent of half the range of one of them, 
or, more exactly, to the extent of the distance on the scale from 
the median to one extreme of one group. 

Wissler ['01] found, in the case of young men and women 
students in Columbia University, that in fatigue at pressing a 
spring with thumb and forefinger, in the perception of weight, 
and in discrimination of points on the skin, there was no appreci- 
able superiority of either sex. Women responded with the 
judgment of ' painful ' to a much less pressure than was required 
in the case of men, but differences in the standard of ' painful ' 
probably played a large part in the effect. Only 18 per cent of 
men judged painful as low a pressure as did the median woman. 
Only 40 per cent of men were as accurate in judging pitch as 
was the median woman, but in the case of size the figure was 
75 per cent. In quickness of reaction time to sound it was 81, 
but in quickness in marking out A's it was only 32 and in quick- 
ness in naming colors it was only 18. In rate of movement 
about 60 per cent of men equaled or surpassed the median woman, 
and in rate of association (by a doubtful test) about 70. In 
memory there was a trifling female superiority. 

Gilbert ['94] measured 100 boys and 100 girls of each age from 
6 to 17, chosen at random from those in school. He gives 
simply the medians and the average variations of the individuals 
therefrom, but it is possible to estimate from his data very closely 
the percentages of boys reaching or exceeding the median for 
girls in the case of the traits listed below. The facts are : In 
the case of boys and girls 8-14 years old (inclusive), the per cent 
of boys reaching or exceeding the median ability for girls of the 
same age is: — 

In delicacy of sense-discrimination for weight 48 

In delicacy of sense-discrimination for color (shades of red) 39 

In reaction time 57 

In resistance to the size-weight illusion 55 

In rate of tapping 64 



The Influence of Sex 31 

In the case of boys and girls 15-17 years old (inclusive), the 
same per cent is : — 

In delicacy of sense-discrimination for weight 58 

In delicacy of sense-discrimination for color (shades of red) 58 

In reaction time 76 

In resistance to the size-weight illusion 68 

In rate of tapping 73 

I have compared the sexes in the case of various abilities, shown 
in objective tests and in school marks, with the results shown below, 
In the case of boys and girls from 8-14 years old (inclusive) the 
per cent of boys reaching or exceeding the median ability for girls 
of the same age is : — 

In tests of the associative and conceptual processes, such as the 
opposites test, alphabet test, word test, addition and multi- 
plication 48 

In speed and accuracy in noticing small details, as in the 

A test, the r-e, o-n, a-t tests and the like 33 

In memory of words for a few seconds (10-30) 40 

In spelHng 33 

In the case of boys and girls of the same classes in high 
schools the same per cent is : — 

In tests of the associative and conceptual processes 50 (approx.) 

In English (Regents' examination and school mark) 41 

In mathematics " " " " " 57 

In Latin " " " " " 57 

In history " " " " " 60 

In the case of college students the same per cent is : — 

In English 35 (approx.) 

In mathematics 45 (approx.) 

History and economics 56 (approx.) 

Mental Science 5° (approx.) 

Modern languages 40 (approx.) 

In the case of college students the selection of women is 
narrower, and probably a little better. The men probably devote 
less time to their college studies. The students in question were 
from two state universities in the north-central states. 

The most important characteristic of these differences is their 
small amount. The individual differences within one sex so 
enormously outweigh the differences between the sexes in these 
intellectual and semi-intellectual traits that for practical purposes 



32 Educational Psychology 

the sex difference may be disregarded. So far as ability goes, there 
could hardly be a stupider way to get two groups alike within 
each group but differing between the groups than to take the 
two sexes. As is well known, the experiments of the past generation 
in educating women have shown their equal competence in school 
work of elementary, secondary and collegiate grade. The present 
generation's experience is showing the same fact for professional 
education and business service. The psychologists' measurements 
lead to the conclusion that this equality of achievement comes 
from an equality of natural gifts, not from an overstraining of 
the lesser talents of women. 

In detail the measurements show a slight inferiority of the male 
sex in receptivity or impressibility and a slight superiority in 
the control of movement and in thought about concrete mechanical 
situations. Dr. Thompson would attribute the last difference 
to differences in training and a charitable male psychologist 
might so attribute the superior quickness of movement also. The 
matter is not of great consequence, first because the differences 
themselves are not, and second because the differences in training, 
if they exist, are probably due largely to original differences 
between the interests of the two sexes. If boys by training learn 
more about the mechanical properties of objects, it is probably 
because they by nature care more about such learning. It can 
hardly be maintained seriously that forced differences in the 
training of these 50 students in the University of Chicago or of 
boys and girls in New Haven and New York, — differences in 
training, that is, apart from the selection of certain training by 
the children's natures, — favored either sex in such a matter as 
solving an example in arithmetic or marking out A's or spelling 
or giving the opposites of words, 

A vast amount of time could be spent in analyses of the minor 
differences reported and in argumentation about the reasons for 
them, for their existence in original nature and for their relations 
one with another. It would be largely profitless, however ; for 
no one of these measurements is by itself very reliable and their 
proper use is only to decide general questions about large differ- 
ences and about the general extent to which sex is the cause 
of the mental variations of mankind. They suffice to prove that 
the sexes are closely alike and that sex can account for only 
a very small fraction of human mental differences in the abilities 



The Influence of Sex 33 

listed. They do not suffice to prove the exact nature or amount 
of the difference in each special trait. 

The trivial difference between the central tendency of men and 
that of women which is the common finding of psychological tests 
and school experience may seem at variance with the patent 
fact that, in the great achievements of the world in science, art, 
invention and management, women have been far excelled by 
men. One who accepts the equality of typical (i. e., modal) 
representatives of the two sexes must assume the burden of 
explaining this great difference in the high ranges of achievement. 

The probably true explanation is to be sought in the greater 
variability within the male sex.* The most gifted men may be 
superior to the most gifted women even though the average 
man is equal to or below the average woman, if men vary zvidely 
enough from their central tendency. Thus in Fig. 16 the central 
tendencies are the same for men and women, but there are two 
men out of every hundred who are superior to all women. In 
Fig. 17 only 45 per cent of men reach the median ability for 
women, but i of the 45 is superior to all women. 

Sex Differences in Variability 

A difference between the sexes in variability may be of as 
great significance as a difference in central tendency. This will 
be clearest if its influence is observed first in one or two imagin- 
ary cases. Suppose, for example, that the average position of 
men on a scale for morality is the same as that for women, 
and call this amount of morality 20 M. Suppose the average 
deviation of individual men from 20 M to be 2 M, and the 
average deviation of women from 20 M to be 3 M. Then the 
two surfaces of frequency would probably be approximately as 
in Fig. 18. The best man would be about twice as good as 

*It should be obvious that the greater variability of males in the sense of 
the divergence of individuals from the average or median or mode of their 
sex implies nothing whatever about the variability of individual men in 
the sense of the divergence of any man's different 'trials' from his own 
general average, — in the sense, that is, of the inconstancy of performance 
of an individual. Men might vary widely inter se, but each man might be 
a very constant performer; women might vary very little from the modal 
woman, yet each one might vary enormously on different occasions from 
her average performance or central tendency. 
3 



34 



Educational Psychology 



the worst man, all men being between about 12 M and 28 M. 
The limits required to include all the women would, on the 
contrary, range from about 8 M to 32 M. The best woman would 




Fig. 16. The continuous line encloses the surface of frequency for men; 
theMotted line, that for women. 





1 


1 






— 1 L 


1 
1 

1 
> 




1 

1 
1 




1 

1 
1 


1 

1 
1 




1 

1 
1 ,., 



Fig. 17. The continuous line is for men; the broken line, for women. 



be four times as good as the worst. About two women out of 
every hundred would be better than the best man ; about two 
would be worse than the worst man. 



The Influence of Sex 35 

Thus, though the average moraUty would be the same, we 
would have differences of tremendous practical moment. The 
great acts of honor, philanthropy, nobility and sacrifice would 
all be due to women. At the same time they would commit 
all the basest of crimes and iniquities. They would lead in all 
moral endeavor, but would also fill the jails and dens of wicked- 
ness, while the men would present lives of equable, uninteresting 
mediocrity of both vice and virtue. If the reader will contemplate 
the practical importance of a similar difference in the variability 
of the sexes in intelligence, originality, musical talent, piety and 



IM. Sivl. IZM. 20 M. i8M- 32M. 

Fig. 18. The status of men and women, the two central tendencies being 
identical, if the men vary only two-thirds as much as the women. 



Other traits, he will see that its measurement is in no wise a 
matter of merely abstract interest. 

In particular, if men differ in intelligence and energy by wider 
extremes than do women, eminence in and leadership of the 
world's affairs of whatever sort will inevitably belong oftener 
to men. They will oftener deserve it. But the greater male 
variability should result also in a great preponderance of men 
amongst the most idiotic idiots. Just this seems to be the case. 
Cattell says ['03, p. 375] in the course of his report on the 
thousand most noted individuals of the civilized world : — 

" I have spoken throughout of eminent men as we lack in 
English words including both men and women, but as a matter 
of fact women do not have an important place on the list. They 
have in all 32 representatives in the thousand. Of these eleven 
are hereditary sovereigns and eight are eminent through mis- 



36 Educational Psychology 

fortunes, beauty or other circumstances. Belleslettres and fiction 
— the only department in which woman has accompHshed much — 
give ten names (of which three are in the first 500) as compared 
with 72 men. Sappho and Joan d'Arc are the only other women 
on the list. It is noticeable that with the exception of Sappho — 
a name associated with certain fine fragments — women have not 
excelled in poetry or art. Yet these are the departments least 
dependent on environment and at the same time those in which 
the environment has been perhaps as favorable for women as for 
men. Women depart less from the normal than man — a fact that 
usually holds for the female throughout the animal series ; in many 
closely related species only the males can be readily distinguished. 
The distribution of women is represented by a narrower bell- 
shaped curve." 

In a study restricted to British genius Ellis ['04, p. lo-ii] finds 
a similar failure of women to reach the extreme of men. 

"In the final result my selection yields 975 British men of a 
high degree of intellectual eminence. The eminent women num- 
ber 55, being in proportion to the men about i to 18. 

A slightly lower standard of ability, it would appear, prevails 
among the women than among the men. On account of the 
greater rarity of intellectual ability in women, they have often 
played a large part in the world on the strength of achievements 
which would not have allowed a man to play a similarly large 
part. It seemed, again, impossible to exclude various women of 
powerful and influential personality, though their achievements 
were not always considerable. I allude to such persons as 
Hannah More and Mrs. Montague. Even Mrs. SomerviUe, the 
only feminine representative of science in my list, could scarcely 
be included were she not a woman, for she was little more than 
the accomplished popularizer of scientific results. In one depart- 
ment, and one only, the women seem to be little, if at all, inferior 
to the men in ability, that is in acting." 

It is well known that very marked intellectual weakness is 
commoner amongst men than amongst women. Two times as 
many men as women will be found in asylums for idiots and 
imbeciles ; and one and a third times as many will be found by 
a census including those cases (commonly somewhat less stupid) 
cared for at home. 

In the case of general ability both extremes of both sexes are 



The Influence of Sex 37 

thus fairly measured for us, but in more specialized traits care- 
ful measurements are needed of the comparative variability of 
men from the typical or ' modal ' man and of woman from the 
' modal ' woman. 

Methods of Comparing the Sexes in Respect to Variability 

When the two groups are equal in respect to their central 
tendencies it is easy to compare their variabilities. For instance, 
in the case of the pressure required to cause a judgment of 
"painful" the results in Dr. Thompson's investigation ['03] 
were that the pressure required ranged from 800 to 3600 grams 
for women and from 800 to 4000 for men. The average deviation 
of the 25 pressures required for the 25 men from that required 
for the average or median man was about 960 grams, while that 
in the case of women was only about 530 grams. Twenty of 
the twenty-five women are included within a range of 1600 
grams, but a range of over 2800 grams is required to include 
twenty of the twenty-five men. If the men and women were 
alike in their central tendencies no objection could be raised to 
comparing their variabilities by the above figures. 

But if the men were markedly less sensitive to pain — if the 
pressure required ranged, for them, from 4000 to 8000, but for 
women from 800 to 3600 — if the median man required 6000 
whereas the median woman required only 2200, — then the greater 
range or greater average deviation of men might not mean a 
greater real variability. For, an objector could properly say, 
the average deviation of butterflies from their average in weight 
is only a small fraction of an ounce whereas the average deviation 
of men from their average is a hundred or more ounces, yet 
butterflies really vary more in weight than men do. Only if one 
man weighs twice as much as another and if one butterfly weighs 
twice as much as another may the variations be called equal in 
the two cases, the objector may continue. Equal variability should 
mean equal ratios, not equal amounts. 

There is obviously much force in this objection, and in the 
recommendation that a variability around a C. T.* of 20 must be 
two times as large as a variability around a C. T. of 10 to be 
properly called equal to it. In certain cases, in fact, this method 

*I shall use C. T. as an abbreviation for Central Tendency. 



C. T. 


9 


C. T. 


i6 


C. T. 


24 



38 Educational Psychology 

is demonstrably just. The absolute or gross variation of sermons 
in length would be much greater than the gross variation 
in the length of the sentences composing them, but really the 
latter are much more variable. Again, 22 individuals worked 
addition examples, first for forty, then for eighty, then for one 
hundred and twenty seconds. The scores were, respectively: — 

A. D.* 2.18 
A. D. 3.41 
A. D. 5.18 

Now the real variability of these 22 individuals in addition is 

substantially the same thing in all three tests. They were not two 

and a half times as much unlike among themselves in the third 

test as in the first! An Average Deviation of 2.18 around a C. T. 

of 9 measures the same fact as an Average Deviation of 5.18 

around a C. T. of 24, If, instead of the gross variabilities 

(2.18, 3.41 and 5.18), we use their ratios to the C.T.s (i. e., 

2.18 3.41 , 5.i8- J V ,, . 

' --t- > and ' or .24, .21 and .22) this sameness 

9 16 24 

in reality is paralleled by the measures. If women tested in 
addition for 80 seconds showed a C. T. of 16 and an A. D. of 
3.4, while men tested for 120 seconds showed a C. T. of 24 
and an A. D. of 5.1, it would certainly be absurd to claim there- 
from that men were one and a half times as variable as women. 

On the other hand, it would be folly to assume that the ratios 
of the gross variabilities to the corresponding C. T.s are 
infallibly fair bases for comparing the real variabilities of groups. 
For instance, tall men vary actually less among themselves in 
stature than do short men. So also men with long middle 
fingers vary actually less in the length of their middle fingers 
than do men with short middle fingers. 

As a matter of theory the allowance to be made for a difference 
in central tendency, when groups are compared in variability 
in a mental trait, should be that obtained by dividing each gross 
variability by the square root of the central tendency rather 
than that obtained by dividing through by the central tendency 
itself. In anatomical measurements empirical facts support this 
theoretical expectation. 

In measurements by scales with arbitrary units, such as school 

* A. D. stands for Average, or Mean, Deviation. 



The Influence of Sex 



39 



marks, any comparison of groups in respect to variability is 
treacherous if the groups differ in central tendency. Thus suppose 
men and women to receives grades in history as follows : — 

Grades 40-44 were given to o men and to 4 women 



45-49 




i( 







It 






10 


50-54 




le 







tt 






23 


55-59 




a 




4 


tt 






61 


60-64 




It 




10 


tt 






75 


65-69 




It 




23 


tt 






61 


70-74 




tt 




61 


tt 






23 


75-79 




it 




75 


tt 






10 


80-84 


i< 


t 




61 


tt 






4 


85-89 




t 




23 


It 








90-94 


<< < 


( 




10 


tt 








95-99 




t 




4 


tt 









The Average Deviation for men and that for women are equal. 
The C. T.s are 62 (60-64) for women and yj (75-79) for men. 
The best women get marks about twice as high as the worst 
women, whereas the best men get marks about one and three- 
fourths times as high as the worst men. But the variability 
of men may be really greater than that of women. For the 
difference called i from 85 to 99 may be very much greater than 
the difference called i from 40 to 54. Moreover the fact that 
the best woman gets marks two times as high as the worst woman 
tells nothing about how many times as much she knows or how 
many times as well she can do. The 'times ' statement is justifiable 
only when the o of the scale means absolute nothingness of the trait 
in question. 80 is twice 40, 84 is twice 42 only if it is twice as 
far from the dividing point between nothing and just barely 
something on the scale for the trait in question. 

In any one mental trait the comparison of men and women 
in variability may thus be ambiguous, but since the central 
tendency for males is below about as often as above that fof 
females, the possibility of error tends in the long run almost equally 
toward exaggeration and toward unfair diminution of male vari- 
ability. So in a score or more of traits taken at random in respect 
to this question, any fundamental difference between the sexes in 
variability should be fairly measured. 



40 Educational Psychology 

The Results of Measurements of Sex Diiferences in Variability 

It is unfortunate that so little information is available for a 
study of sex differences in the variability of mental traits in the 
case of individuals over fifteen. Such statistics as I have been 
able to secure give measures in 26 objective tests, with from 
100 to 1,500 individuals, and in 25 records of school marks with 
from 60 to 1,000 individuals. 

The comparisons in the case of reaction time, reaction time 
with discrimination and choice, and time memory are based on 
the measurements given by Gilbert ['94]. For the data in 
spelling, arithmetic and in the r-e and o-n tests I am indebted 
in part to Messrs. E. L. Earle, W. A. Fox and L. W. Cole. 

The nature of the material, which represents measurements 
taken by different individuals and often with only small groups, 
makes inferences from details unreliable. The data would be 
slightly more accurate if all records had been reduced to a 
common month age at least, but this could not be done with 
the measurements taken by other observers than myself and 
would involve an amount of labor out of proportion to the 
increase in accuracy. The main facts that are relevant to our 
present purpose are as follows : Variability being measured by 
the per cent which the gross variability is of the central tendency, 
the sexes differ as shown in Table 5. 

If the gross variabilities themselves are used, the ratios for 
the A test, a-t test, word test, memory of words and spelling are 
somewhat higher, those for discrimination and reaction time are 
somewhat lower, while those for the opposites test, time memory, 
addition, multiplication, and scholarship remain practically the 
same. The general eft'ect would be to raise the ratios somewhat 
since in the particular tests given the central tendency for girls 
is more often above than below that for boys. 

These facts make it extremeh' probable that, except in the two 
years nearest the age of puberty for girls,* the male sex is 
slightly more variable. From the time of puberty for boys to 
maturity this difference seems to increase rapidly, though the 
records of marks which support this conclusion are not the best 
of evidence. 

The variability of girls with respect to the age at which any 

*The greater variability of girls in these two years is probably a result 
of sex difference in the rate of mental growth. 



The Influence of Sex 41 

TABLE 5- 

Ratio of Female to Male Variability. 

By ages. 9 10 11 12 13 14 15 16 17 

A test 86 I. II 1.04 .94 1.08 1.03 1.07 

A-t test 91 1.05 1.05 1.07 1.35 1-07 -73 

Easy opposites test .97 .81 i.io 1.24 .89 1.15 

Word test 1.05 .91 .85 .87 

Memory (related words) .. . .77 .137 .93 .72 

Memory (unrelated words) . .77 .46 .94 .66 .77 1.28 

Discrimination of length. . . .7*5 .80 .81 .98 1.04 .70 .78 
Simple and discriminative 

reaction time 98 1.21 .98 .93 i.oo i.ii .83 1.14 1.22 

Time memory 56 .75 1.21 .82 .85 1.27 1.26 .66 1.06 

General ratio. Average... .92 1025 .97 

Median .93 1.035 -95 

The chances are i to i that the true result will not vary from the one 
obtained by more than .023 (9-12 yrs.), .04 (13-14 yrs.), .055 (15 yrs.). 

By grades. 4 5 6 7 8 ist high. 

R-e and o-n tests 77 1.19 .97 .82 .85 

Spelling 55 .69 .55 .68 .68 

Addition i.oo .91 1.06 .85 .97 

Multiplication .56 1.15 

In a number of tests (six in all) the ratio of first-year high school girls 
to boys in variability was .975. 

In tests in arithmetic (six in all) the ratio of high school girls to boys 
in variability was .96; in regents' examinations in Latin, English and in 
history, it was .96; in school marks in eight subjects, it was on the average .86. 

In college marks in fourteen different courses the ratios averaged .85. 

given school grade is reached is less than that of boys. The 
difference is not necessarily attributable in its entirety to an original 
difference between the natures of boys and girls. The greater 
variations of boys toward high ages in particular are probably 
due in part to the slower maturing of boys, to the greater 
frequency of temporary withdrawal and to other factors irrespec- 
tive of an original greater variability. But in so far as boys 
are found both younger and older than girls at entrance to a 
grade, the evidence of their greater variability in the complex of 
abilities that determines rate of progress in school is sound. A 
careful estimate will probably show that in this complex girls 
are not over 95 per cent as variable as boys. 

For instance the combined figures for the census of the third- 



42 Educational Psychology 

year high school classes (1908) in Detroit, Fall River, Los 
Angeles, Lowell and Worcester were : — * 

Age 13 14 15 16 17 i8 19 20 and over. Total 
Boys 3 18 113 237 274 154 69 25 893 

Girls I 12 104 298 265 177 40 10 907 

In Chicago (1908) the figures were (the numbers for the 1164 
girls being reduced to a basis of 975) : — 

Age 13 14 15 16 17 18 19 20 and over. Total 

Boys I 34 165 306 291 127 34 17 975 

Girls I 13 127 371 288 132 32 10 974 

In Philadelphia (1908) the figures were (the numbers for the 
872 boys being reduced to a basis of 750) : — 

Age 13 14 15 16 17 18 19 20 and over. Total 

Boys I 3 42 223 256 168 47 10 750 

Girls 31 292 282 III 28 6 750 

In New York (1905. Report of Superintendent of Schools, 
p. 72) the figures were (the numbers for the 1939 girls being 
reduced to a basis of 1356) : — 
Age 13 14 15 16 17 18 19 20 21 and over. Total 
Boys 2 37 274 480 382 123 43 12 3 1356 

Girls 2 48 300 390 454 134 20 3 5 1356 

On the whole boys are twice as frequent as girls in the youngest 
and oldest age groups and about one and one-half times as 
frequent at ages 14 and 19. 

Dr. Thompson does not calculate the variability within either 
sex, nor present the facts on sufficiently fine scales to allow anyone 
else to do it exactly. I have calculated it as well as may be 
from the measurements which she gives, with the result that 
the variability among the 25 women seems on the whole only 
93 per cent of that of the men. The difference is closely the 
same whether the gross variabilities are used directly or are 
first divided by the corresponding" central tendencies or by the 
square roots of the latter. In reaction time, in the rate of 
sorting colors, and in memory the 25 w^omen are more variable ; 
in accuracy in hitting a target, in sensory discrimination and in 

*For the statistics from which these measurements are computed I am 
indebted to the U. S. Bureau of Education, through Prof. G. D. Straycr. 



The Influence of Sex 43 

the tests of ingenuity they are ahnost or quite as variable. But 
in the majority of tests they are less variable. On the whole 
the most probably true estimate is that women are one twentieth 
less variable than men. 

Wissler's results ['01] with college students show female vari- 
ability to be in general about nine-tenths that of males. The 
number of women measured was, however, only 42, and the 
ratio of female to male variability differed greatly in the different 
traits, so that the nine-tenths would, by itself alone, be of no 
great reliability. 

Sex Differences in Traits Not Measured Objectively 

We have now to turn from fairly satisfactory studies of sex 
differences in sensory, motor and intellectual capacities, to a looser 
discussion of the life of feeling, action and general achievement. 
Here objective and precise measurements will seldom be at our 
service. 

There are two studies which do report such differences 
quantitatively, but the data given are subject, unfortunately, to 
whatever errors of prejudice or custom teachers, physicians, and 
German women of intellectual interests make in rating individuals, 
and to possibly important errors due to the existence in their 
minds of different standards for the two sexes. 

Karl Pearson ['04], in securing data on the resemblances of 
children of the same parents, had children rated by their teachers 
for various qualities — as quiet or noisy, shy or self-assertive, 
and the like. The results in the case where a boy and his sister 
were both rated are given in Table 6. If taken at their face 
value they show boys to be somewhat more athletic, noisier, 
more self-assertive, more self-conscious, less popular, duller in 
conscience, quicker-tempered, less sullen, a little duller intel- 
lectually, and less efficient in penmanship, in the exact degrees 
given by Table 6. 

They cannot be thus taken unreservedly ; for, even in comparing 
individuals, opinions about the sexes as total groups might be 
influential and taint the estimates with some measure of current 
irrational prejudices. This error Avould probably increase 
differences beyond their real amounts. Such prejudices, if exist- 
ing, would work still more insidiously in placing the dividing line 
between say keenness and dullness of conscience at a different 



44 Educational Psychology 

point in the case of boys than was assigned to it in the case of 
girls. A boy may not have to be really as conscientious or may 
have to be really more athletic in order to be regarded by current 
standards as equally conscientious or equally athletic in comparison 
with his sister. This error would result in reducing differences 
below their real amounts. However, these measurements are 
much preferable to general announcements of opinion concerning 
boys and girls, unless made by specially competent observers. 



TABLE 6 


). 




Ratings by Teachers of Boys and their Sisters 


IN Respect to Various 


Traits. 








Boys 


Girls 


Athletic 


291 


243 


Betwixt 


12 


9 


Non-athletic 


131 


182 


Quiet 


440 


525 


Noisy 


313 


228 


Shy 


312 


355 


Self-assertive 


262 


218 


Self-conscious 


380 


337 


Unself-conscious 


277 


321 


Popular 


474 


487 


Unpopular 


81 


67 


Conscientiousness 






Keen 


427 


490 


Dull 


260 


197 


Temper 






Quick 


142 


116 


Good-ntaured 


490 


501 


Sullen 


72 


88 


Ability 






Quick-intelligent 


131 


129 


Intelligent 


271 


302 


Slow-intelligent 


280 


273 


Slow 


106 


no 


Slow-dull 


49 


31 


Very dull 


23 


16 


Handwriting 






Very good 


51 


38 


Good 


249 


313 


Moderate 


300 


274 


Poor 


III 


90 


Bad 


15 


II 


Very bad 


3 


2 



The Influence of Sex 45 

The greater variability found for males (see Table 6 under 
Ability and Handwriting) is a sign of the trustworthiness of the 
data ; and the direction of the differences in no case contradicts 
what little objective evidence exists. So the amounts of differ- 
ence are worthy of acceptance until a more adequate study is 
made. They are slight ; there is much overlapping of one sex 
by the other and a far greater range of difference within either 
sex than between the averages of the two. 

On calculating the probable percentages of boys reaching or 
exceeding the degree of each trait that is reached or exceeded by 
half of the girls, we have : — 



61% 


f boys are as athletic as or more athletic than the median girl. 


62% 






noisy 


' noisy 




42% 






shy 


shy 




57% 






self-conscious 


' self-conscious ' 




46% 






popular 


' popular ' 




40% 






conscientious 


' conscientious ' 




56% 






quick-tempered 


' quick-tempered ' 




47% 






intelligent 


' intelligent ' 




43% 




write 


as well as or better 


than the median girl. 





Heymans and Wiersma ['06, '07 and '08] studied mental differ- 
ences of the sexes by means of estimates of individuals made 
by other individuals who knew them more or less intimately. The 
report covered 90 topics, some of which included several traits. 
The individual was graded very coarsely — e. g., as emotional or 
not emotional ; or as a drunkard, an habitual drinker, an occasional 
drinker, or a total abstainer. Such reports are, as has been noted, 
inferior evidence, since the person making them may use different 
standards for men and for women. Thus the same degree of 
emotionality might be called emotional in the case of a man and 
not emotional in the case of a woman, or vice versa. Moreover 
when, as often happens, no rating at all is given in a trait, it 
may be because the condition of the individual to be rated was 
not known in the case of that trait, or because he was on the 
.dividing line between the two classes (or in the case of a single 
judgment, like, "Has he mathematical talent?" lacked the specified 
degree of the quality). Finally, general superstitions about sex 
differences may affect the ratings of individuals. In the case of 
the ratings given by women it seems probable that some of the 
women knew that their ratings were to be used for a study of 



46 Educational Psychology 

sex differences. In the case of the ratings given by men this 
was apparently not so often the case. 

On the whole, the results of the ratings, though very inferior 
to objective measurements, are probably superioi to the mere 
opinions which one could give from reflection on the common 
facts of life and his own narrow circle of acquaintances. They 
may at least serve to make the reader critical of whatever such 
opinions he has. 

The authors do not pretend to distinguish, in the case of any of 
these traits, the differences due to sex itself and the differences 
due to the difference in the training given to girls. They do, 
however, give interesting statements of the difference between 
the present and the previous generation. 

Their own conclusions are that the fundamental differences 
shown by their studies are the greater (i) activity, (2) emotion- 
ality, and (3) unselfishness of the female. They consider women 
to be more impulsive, less efficient intellectually, and more fickle 
than men as a result of the first two differences mentioned above ; 
to be more gifted in music, acting, conversation and the invention 
of stories as a result in part of the second difference ; and to 
think well of people and be easily reconciled to them as a result 
of the third ['07 p. 20]. 

These conclusions are vague and the tables of comparison of 
the sexes which give rise to them are exceedingly long and 
obscure. The latter take the form of 90 classifications such as : — 

From the reports made From the reports made 

almost exclusively by almost exclusively by 

men, the per cents of women, the per cents 

men and of women were : were : 

Emotional 

Not emotional 



Men 


Women 


45 


60 


40 


27 



Men 


Women 


49 


71 


40 


20 



I have therefore calculated from them the probable per cent 
of men reaching or exceeding the median woman in respect to 
each trait, counting the ratings by men and those by women as 
of equal weight. The differences so estimated I have arranged 
roughly in the order of their magnitude. The largest difference is 
that :— 

Only 15 per cent of men are as much more interested in persons than in 
things as the median woman is. 



The Influence of Sex 



47 



The next largest differences are that : — 

In accurate and orderly reten- 
tion of what is read 73% of men equal or excel the median woman. 

In industry 28% 

In adroitness in manual work 28% 

In love of sedentary games of 
skill 71% 

In emotionality 30% 

In temperance in the use of 
alcoholic drinks . . . 30% (or less) 

In independence 70% 

In zeal for money making . . . 69% 

In desire for change 32% 

In impulsiveness 34% 

In quickness of recovery from 
grief 66%" " " " 

Then come the following : 

In activity (of the aimless 

sort) 36% of men equal or excel the median woman. 

In dissatisfaction with oneself 36% 

In religiousness 36% 

In excitability 37% 

In sympathy 38% 

In patience 38% 

In love of sports 62% 

In humor 61% 

In risibility 39% 

In talkativeness 40% 

In gaiety 40% 

In vanity of person 40% 

There are very slight differences as follows : men are a little 
oftener reported as critical, attached to opinions once formed, 
given to ambitious plans, given to contradiction, sensible, decisive, 
gifted in mathematics, gifted in literature, specific, of good 
memories, fond of eating and drinking, fond of distinction, strict, 
and also easy-going, in discipline with children, kind to sub- 
ordinates, widely read, and punctual. They are a little less 
often reported as good-natured, anxious, easily reconciled after 
anger, insistent on immediate results, good judges of human 
nature, practically resourceful, narrow, gifted in languages, 
gifted in music, good observers, thrifty, domineering, kind and 
careful in discipline with children, active in philanthropic work, 
demonstrative, honest about money, fond of intercourse with social 



48 Educational Psychology 

superiors, timid, well posted about the affairs of acquaintances, 
polite, attentive, tidy, and courageous in sickness. 

In the following traits there is still less difference reported or 
no difference observable: Trustfulness, tolerance, inconstancy in 
sympathies, devotion to old memories, quickness in comprehension, 
superficiality, stupidity, ability in drawing, acting, mimicing, ear 
for music, patriotism, naturalness, straightforwardness, truthful- 
ness, kindness to animals, snobbishness, courage, and pleasure- 
seeking. 

It is not desirable to comment further on these results of 
Heymans' and Wiersma's work, until further study by more 
objective methods has been given to the topic. 

It would be desirable in any such study that the sex differ- 
ences in the instinctive acts, interests, aversions and emotional 
responses should be studied apart from the differences in similar 
traits that have been produced by circumstances. Two instincts 
are worthy of special attention. The most striking difference in 
instinctive equipment consists in the strength of the fighting 
instinct in the male and of the nursing instinct in the female. 
No one will doubt that men are more possessed by the instinct 
to fight, to be the winner in games and serious contests, than 
are women ; nor that women are more possessed than men by 
the instinct to nurse, to care for and fuss over others, to relieve, 
comfort and console. And probably no serious student of human 
nature will doubt that these are matters of original nature. iThe 
out and out physical fighting for the sake of combat is pre- 
eminently a male instinct and the resentment at mastery, the 
zeal to surpass and the general joy at activity in mental as well 
as physical matters seem to be closely correlated with it. It has 
been common to talk of women's "dependence." This is, I am 
sure, only an awkward name for less resentment at mastery. The 
actual nursing of the young seems likewise to involve equally 
unreasoning tendencies to pet, coddle, and "do for" others. The 
existence of these two instincts has been long recognized by 
literature and common knowledge, but their importance in causing 
dift'erences in the general activities of the sexes has not. The 
fighting instinct is in fact the cause of a very large amount of 
the world's intellectual endeavor. The financier does not think 
merely for money nor the scientist for truth nor the theologian 
to save souls. Their intellectual efforts are aimed in great 



The Influence of Sex 49 

measure to outdo the other man, to subdue nature, to conquer 
assent. The maternal instinct in its turn is the chief source of 
woman's superiorities in the moral life. The virtues in which 
she excels are not so much due to either any general moral 
superiority or any set of special moral talents as to her original 
impulses to relieve, comfort and console. \ 

Training undoubtedly accentuates these inborn differences 
since boys play more with boys and are trained more by men, the 
opposite holding with girls. A reversal of training by which 
girls would be surrounded by the social milieu now affecting 
boys would, as we often see in isolated cases, lessen the sex 
difference, i But we may be sure that if we should keep the 
environment of boys and girls absolutely similar these instincts 
would produce sure and important differences between the mental 
and moral activities of boys and girls. \ 

Since these differences in instinctive equipment are true causes 
it seems wise not to invoke other less probable traits to account 
for any fact which these seem fairly adequate to explain. For 
instance, if the intellectual achievement of men was found to be 
superior to that of women we could explain it either by the 
indirect effect of physical strength and bodily fitness or by an 
actual difference in intellect or by the zeal and activity due to 
the fighting instinct. Our rule would be to exhaust first the 
influence of the known physical differences and second the 
influence of the instinct in question. Only if these were 
inadequate should we resort to the hypothetical cause of differ- 
ences in purely intellectual caliber. 

Havelock Ellis ['94, '04] chooses as general sex differences 
the less variability and the greater affectability and primitiveness 
of the female mind. The first point has been discussed fully. By 
affectability he means not only greater impressibility by and 
responsiveness to stimuli of all sorts, but also less inhibition of 
the emotions and other instinctive reactions. The fact seems 
indubitable though its exact amount can not be even roughly 
estimated. Not only the superiority in tests of perceptual power 
and the greater suggestibility which we have noted, but 
also the relative frequency of dreams, trance states and emotional 
outbreaks and the common differences between our treatment of 
the men and of the women with whom we are associated, witness 
to it. In his evidence for the discussions of the primitive nature 

4 



50 Educational Psychology 

of vvomeii Mr. Ellis scoms to have physique in view primarily. 
How far women resemble uncivilized races and children in mental 
make-up is, to me at least, not at all clear. 

The same author emphasizes, as so many others have done, the 
fact of female dependence or lack of aggressiveness in intellect. 
The ([ualilies that we call original, constructive, organizing and 
critical are ill delnK-d and comparisons are hard to arrange 
because men and women have devoted the active power of the 
intellect to such different fields. Comparison of the most eminent 
representatives from both sexes is obviously unfair in so far as 
men are more variable. 

If we are to believe the novelists and playwrights, women are 
more concerned with their own feelings and personalities than 
nun, are emotionally more subjective. This is not inconsistent 
with the existence of greater sympathy of the motherly sort, nor 
with the possibly superior gifts of men in the examination and 
intellectual manipidation of subjective conditions. An interesting 
bit of evidence supports the conventional view of fiction. Many 
people carry on as a systematic day dream a continued story 
in which they figure and which ])ossesses its interest from the 
chance il gives to think pleasantly of oneself. According to 
Learoyd | '96] three and a half times as many women as men 
do this (46.7 per cent and 13.5 per cent). 

On the whole the difl'erences reported in the case of the less 
easily measurable features of intellect, character and behavior 
are of the same order of magnitude as those found in objective 
tests. They do not require any amendment of the general rule 
that sex is the cause of only a small fraction of the differences 
between individuals. The differences of men from men and of 
women from women are nearly as great as the ditTereuces between 
men and women. 



CHAPTER IV 
The Influence oe Remote Ancesiuy ou Race 

The Possibility of Racial Mental Differences 

Men are mentally like one another and unlike dogs or horses 
because men spring from a presumably common remote ancestry 
which was not the ancestry of dogs and horses. Men, dogs and 
horses are more alike mentally than men, dogs, horses, earth- 
worms and clams arc, because presumably men, dogs and horses 
spring from a common ancestry which was not the ancestry of 
earthworms or clams. Certain men, for example the American 
Indians, springing from a common ancestry which was not the 
ancestry of Europeans, may be expected to be mentally more 
like one another than like Europeans, if their common ancestry 
differed mentally from that of Europeans. 

A distinct race is a group of men who to a considerable extent 
have in common the same remote ancestry, its present descendants 
being to a considerable extent confined to that group. The more 
they all hark back to just the same ancestry, and the more 
exclusively they represent the present product of this ancestry, 
the more distinct a race they will be. 

A race that is thus distinct in ancestry is commonly distinct 
in some physical traits also. If its remote ancestry differed from 
the remote ancestry of other races in mental traits, as it probably 
did to at least some slight extent, the race has a probability of 
differing from other races in these traits. So also if the race 
has differed from other races in the nature or amount of selection, 
natural or artificial, on the basis of mental traits. An individual 
may thus, by original nature, possess certain racial mental 
tendencies. His position on the scale for any mental trait may 
be due in part to his membershii) in a certain race, — that is, to 
his origin from a certain remote ancestry. 

The influence of remote ancestry cannot however be isolated 
for measurement at all perfectly. The pedigrees of human stocks, 

(51) 



52 Educational Psychology 

at least of the modern civilized stocks, are not clear enough, and 
the influence of similarity in remote ancestry is hard to distinguish 
from that of similarity in training. Many of the mental similarities 
of an Indian to Indians and of his differences from Anglo-Saxons 
disappear if he happens to be adopted and brought up as an 
Anglo-Saxon. 

So, though the best way to think of the problem is to pictuife 
the hereditary relations of all men and to measure the original like- 
nesses within the same strains and the dilTorences between strains, 
apart from all influences of training, the facts at hand do not so 
group themselves. The facts are measurements of the differences 
between groups which are distinct to an unknown degree in traits 
which are influenced by training to an unknown degree. Any 
conclusion will depend upon one's estimates of these two unknown 
quantities. 

I shall report one sample study of the topic in the case, of great 
importance to American education, of differences between whites 
and negroes in scholarship in the high school. I shall then sum- 
marize the results of other measurements of racial mental differ- 
ences ; and. lastly, describe the attitude which science recommends 
toward the apparently original differences in intellect, character 
and temperament which have not been measured. 

A Sample Study of Racial Differences 

Mr. Mayo [in a study as yet unprinted] secured the academic 
records of 150 negroes* who entered the high schools of New 
York City during the period from 1902 on. For each such 
record he got a white pupil'sf record selected under the same 
conditions. It is iiupossible to tell exactly whether and how far 
the two groups of pupils thus taken represent dissimilar samplings 
of the two total groups, negroes and whites in New York City. 
In my opinion the samplings are closely similar. There are no 
measurements of the extent to which residence in New York 
selects the more scholarly of negroes from the country, or of the 
extent to which entrance to high school selects differently from 

*A negro being defined as an individual reported as a negro by school, 
officers. MuUittoes arc of course frequent. 

f A white pupil being defined as an individual reported as such by school 
officers. There may in rare cases have been some slight mixture of negro 
blood. 



The Influence of Remote Ancestry or Race 53 

the negroes in New York than from the whites. In general, 
selection by entrance to the public high schools is narrow but 
democratic ; and in Mr. Mayo's opinion and my own the high 
school gets a somewhat, but not much, higher selection from the 
colored than from the white youth. That is, in our opinion, the 
superiority of the colored in high school to the colored outside is 
greater, but not much greater, than the superiority of the whites in 
high school to the whites outside. 

Whatever be the difference in the selection of the two groups, 
colored beginners in high schools in New York City differ from 
whites in their careers there as follows : 

( 1 ) On the average they are seven months older, only 36 per cent 

of them being as young as the median white. 

(2) They continue in the high school longer. 

(3) In achievement in the different studies they are somewhat, 

but not very much, inferior. The general tendency is for 
only three-tenths of them to reach the median record for 
whites. 

(4) The difference is greatest in the case of English, in which 

only 24 per cent of the colored pupils reach or exceed 
the median for whites. 

Table 7 gives a sample of Mr. Mayo's measurements of the 
differences. Fig. 19 presents the facts graphically. 

Mr. Mayo also measured the differences in variability, as far 
as he could from the arbitrary measures afforded by school marks. 
For the details the reader must turn to the full tables in his report 
(which will be printed at an early date), one sample table and 
the general drift of the results being all that can be presented 
here. The records of colored pupils were perhaps a very little 
less variable than the whites. Thus, in the score for total scholar- 
ship (Table 7), 80 per cent of the colored pupils are included 
within a range of 193^2 points on the scholarship scale, while to 
include 80 per cent of the white pupils requires a range of 20 
points. The corresponding figures for the inclusion of 60 per cent 
are 143^ and 14 points. The figures for the inclusion of 50 
per cent are 9 and lo^^. The figures for the inclusion of 90 per cent 
(or, to be exact, 90.7 per cent) are 33 and 31. The comparison 
in variability is, as in the case of the sexes, of great practical 
importance. The ability of a hundred of its most gifted represent- 
atives often counts more for a nation's or a race's welfare than 



54 



Educational Psychology 



the ability of a million of its mediocrities. The fact that the 
colored pupils, though clustered more closely at the center, range 
to nearly or quite as high grades as do the white is thus noteworthy. 

TABLE 7. 
White and Colored Pupils Compared in Scholarship in New York 

City High Schools. 
Median of all marks 



in the first trials (that 


Number 


Number 


is, excluding marks 


of 


of 


for courses repeated 


white 


colored 


after failure) 


pupils 


pupils 


24—25 


. . 


I 


26 — 27 


. . 


. . 


28 — 29 


. . 






30—31 








32 33 


I 






34—35 


I 






36—37 


. . 






38—39 


. . 






40—41 


I 


5 


42—43 


2 


. . 


44—45 


• . 


2 


46—47 


. . 


2 


48 49 




I 


50—51 


4 


21 


52—53 


4 


6 


54—55 


I 


9 


56—57 


2 


7 


58—59 


6 


12 


60 — 61 


18 


17 


62—63 


21 


22 


64—65 


13 


16 


66—67 


12 


13 


68—69 


II 


15 


70—71 


10 


2 


72—73 


16 


I 


74—75 


8 


3 


76—77 


3 


3 


78—79 


4 


I 


80—81 


5 




82—83 


2 


3 


84—85 


2 


I 


86—87 


. , 


, , 


88—89 


. . 


I 


90 91 


2 




92 93 


I 




I 



Median 



66 



62 



The Influence of Remote Ancestry or Race 



55 



The Results of Measurements of Racial Mental Differences 

In summarizing the measurements of racial mental differences 
I shall in the main quote the admirable account by Woodworth 

['10]. 

The different races of men have been compared by objective 
measurements in respect to the keenness of the senses, but in 
few traits besides. The reports of travelers gave rise to the 
doctrine that primitive races excelled modern Europeans in powers 



I — I 



HE 



.1/1.. 



20 



40 



60 



80 



dk 



Fig. 19. Comparison of white pupils (continuous line) and colored pupils 
(dotted line) in respect to scholarship in the high school. The horizontal 
scale is for the median of all marks obtained by an individual except those 
obtained in courses repeated because of failure. The marks in these schools 
are on a o - 100 scale. 

of vision, hearing and smell. Skepticism concerning this doctrine 
has led to many measurements by anthropologists. 

"Ranke on testing natives of Brazil, a race notable for 
its feats of vision, found that their ability to discern the position 
of a letter or similar character at a distance, though good, was 
not remarkable, but fell within the range of European powers. 
The steppe-dwelling Kalmuks, also renowned for distant vision, 
being able to detect the dust of a herd of cattle at a greater 
distance with the naked eye than a European could with a 
telescope, have also been examined ; and their acuity was indeed 
found to be very high, averaging considerablv above that of 



56 Educational Psychology 

Europeans ; yet only one or two out of the forty individuals 
tested exceeded the European record, while the great majority 
fell within the range of good European eyes. Much the same 
result has been obtained from Arabs, Egyptians and quite a 
variety of peoples. Among the most reliable results are those 
of Rivers on a wholly unselected Papuan population. He found 
no very exceptional individual among 115 tested, yet the average 
was somewhat better than that of Europeans. I had myself, 
through the kindness of Dr. McGee, the opportunity of testing 
individuals from quite a variety of races at the St. Louis Fair 
in 1904, and my results agree closely with those already cited, 
though I did not find any cases of very exceptional powers among 
about 300 individuals. There were a number who exceeded the 
best of the 200 whites whom I also tested under the same 
conditions, but none who exceeded or equaled the record of a 
few individuals who have been found in the German army. 
Indians and Filipinos ranked highest, averaging about 10 per cent 
better than whites, when all individuals of really defective vision 
were excluded. The amount of overlapping is indicated by stating 
that 65-75 P^'" cent of Indians and Filipinos exceeded the average 
for whites." ['10, p. 175] 

There are racial differences in hearing, as tested by the ticking 
of a watch or a click artificially made. The Papuans were found 
to be inferior to Europeans. Bruner ['08, p. 92] found that 
only five per cent of Filipinos equalled or exceeded the median 
white American, The per cent for Indians with more or less 
school training was 38. Of the 18 Patagonians, Ainus and 
reputed Pygmies, none equalled the median white American. 
These differences are probably due in large measure and possibly 
in toto to the greater cleanliness, freedom from injury to the ear, 
and special training in hearing a click transmitted by a telephone 

Of the sense of touch and the sense of pain Woodworth says : 

"The sense of touch has been little examined. McDougall found 
among the Papuans a number with extremely fine powers of dis- 
crimination by the skin. The difference between two points and 
one could be told by these individuals even when the two points 
were brought very close together ; on the average, the Papuans 
tested excelled Europeans considerably in this test. On the other 
hand, Indians and Filipinos, and a few Africans and Ainu, tested 
in the same manner, seem not to differ perceptibly from whites. 



The Influence of Remote Ancestry or Race 57 

The pain sense is a matter of some interest, because of the 
fortitude or stoHdity displayed by some races towards physical 
suffering. It may be, and has been conjectured, that the sense 
for pain is blunt in these races, as it is known to be in some 
individuals who have allowed themselves to be burned without 
flinching, and performed other feats of fortitude. The pain 
sense is tested by applying gradually increasing pressure to some 
portion of the skin, and requiring the person tested to indicate 
when he first begins to feel pain. Now as a matter of fact, the 
results of McDougall on the Papuans, and those of Dr. Bruner 
and myself on Indians, Filipinos, Africans and Ainu, are in close 
agreement on this point. Greater pressure on the skin is needed 
to produce pain in each of these races than in whites. This is 
the average result, but in this test the distribution of the cases is 
specially important. Though most whites feel pain at or about a 
certain small pressure, there is quite a respectable minority who 
give no sign till much higher pressures are reached, their results 
corresponding very closely to those of the majority of Indians. 
And similarly, a minority of Indians feel pain at much lower 
pressures than the bulk of their fellows, falling into the ranks 
of the white man. In each group, the distribution is bimodal, or 
aggregated about two points instead of one ; but whites are prin- 
cipally aggregated about the lower center, and Indians and other 
races about the higher center. Introspection comes to our aid in 
explaining this anomaly, for it shows that there is some difficulty 
in telling just when the pressure becomes painful. If one is 
satisfied with slight discomfort, a moderate pressure will be 
enough ; but if a sharp twinge is demanded, the pressure must 
be considerably increased. Most whites, under the conditions of 
the test, are satisfied with slight discomfort, while my impression 
in watching the Indians was that they were waiting to be really 
hurt. The racial difference would accordingly be one in the 
conception of pain, or in understanding the test, rather than in 
the pain sense. 

On the whole, the keenness of the senses seems to be about on 
a par in the various races of mankind." ['10, pp. 176-177] 

With respect to racial differences in speed of brain action and 
in certain objective, though somewhat trivial, tests of intellect, 
Woodworth says : 



58 Educational Psychology 

"Some interest attaches to tests of the speed of simple mental 
and motor performances, since though the mental process is 
very simple, some indication may be afforded of the speed of 
brain action. The reaction time test has been measured on 
representatives of a few races, with the general result 
that the time consumed is about the same in widely different 
groups. The familiar "tapping test," which measures the rate 
at which the brain can at will discharge a series of impulses to 
the same muscle, was tried at St. Louis on a wide variety of folk, 
without disclosing marked differences between groups. The 
differences were somewhat greater when the movement, besides 
being rapid, had to be accurate in aim. The Eskimos excelled 
all others in this latter test, while the poorest record was made 
by the Patagonians and the Cocopa Indians — which groups were, 
however, represented by only a few individuals. The Filipinos, 
who were very fully represented, seemed undeniably superior to 
whites in this test, though, of course, with plenty of over- 
lapping 

"Equitable tests of the distinctly intellectual processes are hard 
to devise, since much depends on the familiarity of the material 
used. Few tests of this nature have as yet been attempted on 
different races. 

"There are a number of illusions and constant errors of judgment 
which are well known in the psychological laboratory, and which 
seem to depend, not on peculiarities of the sense organs, but on 
quirks and twists in the process of judgment. A few of these 
have been made the matter of comparative tests, with the result 
that peoples of widely different cultures are subject to the same 
errors, and in about the same degree. There is an illusion which 
occurs when an object, which looks heavier than it is, is lifted 
by the hand ; it then feels, not only lighter than it looks, but even 
lighter than it really is. The contrast between the look and the 
feel of the thing plays havoc with the judgment. Women are, 
on the average, more subject to this illusion than men. The 
amount of this illusion has been measured in several peoples, and 
found to be, with one or two exceptions, about the same in all. 
Certain visual illusions, in which the apparent length or direction 
of a line is greatly altered by the neighborhood of other lines, 
have similarly been found present in all races tested, and to about 
the same degree. As far as they go, these results tend to show 



The InUiience of Remote Ancestry or Race 59 

that simple sorts of judgment, being subject to the same disturb- 
ances, proceed in the same manner among various peoples ; so 
that the similarity of the races in mental processes extends at 
least one step beyond sensation. 

"The mere fact that members of the inferior races are suitable 
subjects for psychological tests and experiments is of some value 
in appraising their mentality. Rivers and his collaborators 
approached the natives of Torres Straits with some misgivings, 
fearing that they would not possess the necessary powers of sus- 
tained concentration. Elaborate introspections, indeed, they did 
not secure from these people, but, in any experiment that called 
for straightforward observation, they found them admirable 
subjects for the psychologist. Locating the blind spot, and 
other observations with indirect vision, which are usually 
accounted a strain on the attention, were successfully per- 
formed. If tests are put in such form as to appeal to the 
interests of the primitive man, he can be relied on for 
sustained attention. Statements sometimes met with to the 
effect that such and such a tribe is deficient in power of 
attention, because, when the visitor began to quiz them on 
matters of linguistics, etc., they complained of headache and ran 
away, sound a bit naive. Much the same observations could be 
reported by college professors, regarding the natives gathered in 
their class rooms. 

"A good test for intelligence would be much appreciated by the 
comparative psychologist, since, in spite of equal standing in 
such rudimentary matters as the senses and bodily movement, 
attention and the simpler sorts of judgment, it might still be 
that great differences in mental efficiency existed between different 
groups of men. Probably no single test could do justice to so 
complex a trait as intelligence. Two important features of 
intelligent action are quickness in seizing the key to a novel 
situation, and firmness in limiting activity to the right direction, 
and suppressing acts which are obviously useless for the purpose 
in hand. A simple test which calls for these qualities is the 
so-called "form test," There are a number of blocks of different 
shapes, and a board with holes to match the blocks. The blocks 
and board are placed before a person, and he is told to put the 
blocks in the holes in the shortest possible time. The key to 
the situation is here the matching of blocks and holes by their 



6o Educational Psychology 

shape; and the part of intelligence is to hold firmly to this 
obvious necessity, wasting no time in trying to force a round 
block into a square hole. The demand on intelligence certainly 
seems slight enough ; and the test would probably not differentiate 
between a Newton and you or me; but it does suffice to catch 
the feeble-minded, the young child, or the chimpanzee, as any of 
these is likely to fail altogether, or at least to waste much time 
in random moves and vain efforts. This test was tried on 
representatives of several races and considerable differences 
appeared. As between whites, Indians, Eskimos, Ainus, Filipinos 
and Singhalese, the average differences were small, and much 
overlapping occurred. As between these groups, however, and 
the Igorot and Negrito from the Philippines and a few reputed 
Pygmies from the Congo, the average differences were great, and 
the overlapping was small. Another rather similar test for 
intelligence, which was tried on some of these groups, gave them 
the same relative rank. The results of the test agreed closely 
with the general impression left on the minds of the experimenters 
by considerable association with the people tested. And, finally, 
the relative size of the cranium, as indicated, roughly, by the 
product of its three external dimensions, agreed closely in these 
groups with their appearance of intelligence, and with their 
standing in the form test. If the results could be taken at their 
face value, they would indicate differences of intelligence between 
races, giving such groups as the Pygmy and Negrito a low 
station as compared with most of mankind. The fairness of the 
test is not, however, beyond question ; it may have been of a 
more unfamiliar sort to these wild hunting folk than to more 
settled groups. This crumb is, at any rate, about all the testing 
psychologist has yet to offer on the question of racial differences 
in intelligence." ['lo, pp. 179-181] 

The difference between civilized whites and Negritos mentioned 
by Professor Woodworth is shown graphically in Fig. 20 for 
the first trial in placing the blocks and in Fig. 21 for the third 
trial. In the first trial only gj4 per cent of the Negritos were 
as quick as the median white ; in the third trial no one of them 
was, the best individual of the twenty-twa just not reaching the 
speed of the median w^hite. The Negritos also made many more 
errors. The reputed Pygmies were still less capable than the 
Negritos. The Pygmies apparently did not do so well in this 



The Influence of Remote Ancestry or Race 



6i 



test as the so-called 'feeble-minded' and 'higher grade imbeciles' 
confined in state asylums in Massachusetts and Connecticut. 

Havelock Ellis ['04] studied the relation of race to amount and 
kind of achievement in the case of the 1030 most eminent British 
careers from the 4th to the 19th century. He verifies the opinion 
that the Scotch have a larger percentage of men of great intellect 
than the English, Welsh or Irish. The most marked difference 



I 



1 
I 

! r 



15 



150 



15 30 45 60 75 90 105 



Fig. 20 (upper diagram). Comparison of whites (continuous lines) and 
Negritos (dotted lines) in respect to time taken 'to put variously shaped 
blocks in holes to match. The horizontal scale is for. time in seconds, first 
trial. 



Fig. 21 (lower diagram), 
third trial were used. 



As in Fig. 20, except that the records in the 



which he finds is between the Scotch and Irish in the case of 
ability in Science and in Acting. Of the 120 men of science, 21 
were Scotch and only i Irish, while of the 42 actors 6 were Irish 
and none were Scotch. He also finds signs of differences in the 
character of the scientific work done by men from different sec- 
tions representing somewhat different racial stocks. He writes : 



62 Educational Psychology 

'Tsychologically it is not difficult to detect a distinct character 
in English scientific genius, according as it springs from the 
Anglo-Danish district or the East-Anglian focus or the south- 
western focus, although I am not aware that this has been pointed 
out before. The Anglo-Danish district may here be fairly put 
first, not only on account of the large number of scientific men it 
has wholly or in part produced, but also on account of the very 
high eminence of some among them. The Anglo-Dane appears 
to possess an aptitude for mathematics which is not shared by the 
native of any other English district as a whole, and it is in the 
exact sciences that the Anglo-Dane triumphs.* Newton is the 
supreme figure of Anglo-Danish science ; it will be noted that 
he belongs to the East-Anglian border, and by his mother is 
claimed by Rutland, a little county which, I am inclined to think, 
really belongs psychologically and perhaps ethnologically to East 
Anglia. The combination of the Anglo-Dane and the East 
Anglian seems highly favorable to scientific aptitude ; the abstract- 
ing tendency of the Anglo-Dane, and the exaggerated 
independence of his character, with the difficulty he finds in taking 
any other point of view than his own, are happily tempered by 
the more cautious and flexible mind of the East Anglian. Darwin 
(who also belonged to the Welsh Border) belonged in part, like 
Newton, to the East Anglian border of the Anglo-Danish district, 
and also (somewhat remotely) to Norfolk, a county which con- 
tains many Danish elements. The science of the Anglo-Danish 
district is not exclusively mathematical, and geology especially 
owes much to the Anglo-Dane ; it will be remembered that geology 
was one of the first sciences to attract Darwin. 

" The East Anglian is in scientific matters drawn to the concrete, 
and shows little or no mathematical aptitude. He is a natural 
historian in the widest sense. He delights in the patient collection 
of facts, and seeks to sift, describe, co-ordinate, and classify them. 
In his hands science becomes almost an art. Gilbert illustrates 
East Anglian scientific methods in the inorganic world, Ray in 
the organic, and Francis Bacon, though he cannot himself be 
classed among men of science, has in the Novum Organum and 
elsewhere presented a picture of scientific method as it most 
naturally appears to the East Anglian mind, 

*The mathematical tendencies of Cambridge are due to the fact that 
Cambridge drains the ability of nearly the whole Anglo-Danish district. 



The Influence of Remote Ancestry or Race 63 

"It is not easy to see anything- specific or definitely Brythonic 
in the scientific activities of the Welsh Border. At most it may 
be said that there is some tendency for science here to take on a 
technological character and to become associated with the artistic 
crafts. The scientific men found here often belong only in 
part to the district, and many of them seem to possess the 
psychological characters of the southwestern focus. 

"The scientific characters of the southwestern focus are quite 
clear, and definitely distinct from those of either the Anglo- 
Danish district or the East Anglian focus. What we find here 
is the mechanical impulse, and more especially the physiological 
temper, the instinct to seek out the driving forces of vital 
phenomena. It is on this account that Harvey, though of 
Kentish family, may be said to belong psychologically to this 
focus, as also Stephen Hales, though he belonged partly to 
Kent and partly to East Anglia. The great scientific physicians 
belong here (the surgeons are largely East Anglian), with 
Sydenham at the head and Glisson. Huxley, again, is a typical 
figure. Inventors are numerous, for the scientific men of this 
region have frequently been enamoured of practical problems, 
and just as they have been pioneers in the physical world, so 
in science they have sought rather to make discoveries than 
to formulate laws. Thus in astronomy we have Adams, and 
one of the greatest and most typical scientific men of this region 
was Thomas Young." ['04, pp. 68-71] 

These last differences are not measured, but if they exist at 
all they are surely very slight ; for even the most striking differ- 
ence, that between the Scotch and Irish in science and in acting, 
is really a very small difiference. Even supposing circumstances 
of religion, education and the like to have had no part in it 
and so attributing the whole of the difference found to race, the 
facts found could be explained by supposing the two races to 
differ in the capacity for science by much less than the amount 
shown in Fig. 22. Similarly in the case of acting. A very slight 
difference between two groups in central tendency may (and 
will, except for contrary influences from differences in variability) 
make an enormous difference between the percentages from the 
two groups that possess a very high degree of the trait in question. 
Indeed I have quoted Ellis's conjectures chiefly as a sample of 
how, on the one hand, a striking difference between extreme 



64 Educational Psychology 

representatives may mislead one and of how, on the other hand, 
a very small general difference between two races may by its 
effect in producing many more men of very high ability, advance 
the social condition of the favored race. 

The Interpretation of the Differences Betzveen One Race and 

Another in Achievement 

The moderation of the findings by psychologists is in striking 
contrast with the first and common impression made by the 
history and present status of different races of men. The modern 
European, who can kill a hundred of a race in an hour, or buy 
up their entire property with the results from one day of his 




Fig. 22. 

labor, or get any of the results one of them desires in a tenth 
of the time that they take, seems to be far more capable than 
they. The Chinese, who resists all that we think he ought to 
crave, seems obviously to have a temperament radically different 
from ours. Large, glaring differences mark the achievements of 
races and seem to need large differences in nature as their origins. 
The most noticeable fact about the races of men seems to be 
their great mental variety. Under the deliberate scrutiny of 
actual measurements, however, what seemed to be large differ- 
ences shrink to five or ten per cent, and what seemed to be wide 
gaps are bridged. No two races have been measured which 
do not overlap mentally whatever be the trait measured. 

The first thing to note in respect to the apparent conflict 
between common observation and precise experiments is that the 
two have not measured the same traits. Common observation 
of the African and the European, for example, decides that the 
latter is superior in intellect, enterprise and self-reliance. Even 



The Influence of Remote Ancestry or Race 65 

when experiments show him to be approximately equal in sense 
keenness, resistance to the size-weight illusion, or putting blocks 
in holes that fit them, the claims of common observation are 
not necessarily denied. The nature and amount of race differ- 
ences in such traits as intellect, enterprise and self-reliance cannot 
be inferred from the amount of difference found in sensory or 
sensori-motor traits, but must be studied directly. We do not 
know just what the symptoms of intellect are, but apparently 
quickness and accuracy in making purely mental associations, 
ability to respond to parts or elements of situations which cannot 
be abstracted in reality but only in thought, the consequent power 
to devise new responses to old situations, and a marked develop- 
ment of the instinctive satisfaction in thought for its own sake 
are leading ones. Measurements of these traits in different races 
are much needed. In the second place, two races need not be 
equally gifted because each is equally well adapted to its environ- 
ment, if the second race has by superior enterprise sought out 
or created a more exacting but also more remunerative 
environment. The Bushman may count all that he needs to count, 
but to put oneself in a position that needs algebra and the 
calculus may itself be a symptom of superiority. So the complex 
of qualities which is called enterprise remains largely untouched 
by the psychologist's tests. The very fact that a certain test 
seems to be unfair to the Bushman may be evidence of his 
inferiority. 

A third fact for consideration is that although the most rigorous 
thinkers amongst anthropologists are skeptical concerning original 
mental racial differences, the general body of scientific opinion 
is by no means fully agreed with them. Francis Galton ['69, '92] in 
a well known chapter on "The Comparative Worth of Different 
Races" declares that, taking negroes on their own intellectual 
ground, they still are inferior to Europeans by about one- 
eighth of the difference between say Aristotle and the lowest 
idiot. That is, he considers the two groups to differ approxi- 
mately as shown in Fig. 23. His argument is: 

"Thirdly, we may compare, but with much caution, the relative 
position of negroes in their native country with that of the 
travellers who visit them. The latter, no doubt, bring with them 
the knowledge current in civilized lands, but that is an advantage 
of less importance than we are apt to suppose. A native chief 
5 



66 Educational Psychology 

has as good an education in the art of ruling men as can be 
desired ; he is continually exercised in personal government, and 
usually maintains his place by the ascendency of his character, 
shown every day over his subjects and rivals. A traveller in 
wild countries also fills, to a certain degree, the position of a 
commander, and has to confront native chiefs at every inhabited 
place. The result is familiar enough — the white traveller almost 
invariably holds his own in their presence. It is seldom that 
we hear of a white traveller meeting with a black chief whom 
he feels to be the better man. I have often discussed this subject 
with competent persons, and can only recall a few cases of the 
inferiority of the white man, — certainly not more than might be 
ascribed to an average actual difference of three grades, of which 
one may be due to relative demerits of native education, and the 
remaining two to a difference in natural gifts. 



Fig. 23. The original difference between Europeans (continuous line) and 
Negroes (dotted line) in intellectual ability, according to Galton. 

"Fourthly, the number among the negroes of those whom we 
should call half-witted men is very large. Every book alluding 
to negro servants in America is full of instances. I was myself 
much impressed by this fact during my travels in Africa. The 
mistakes the negroes made in their own matters were so childish, 
stupid, and simpleton-like, as frequently to make me ashamed 
of my own species. I do not think it any exaggeration to say, 
that their c is as low as our e, which would be a difference 
of two grades, as before. I have no information as to actual 
idiocy among the negroes — I mean, of course, of that class of 
idiocy which is not due to disease." [Hereditary Genius, 2nd 
Edition, '92, p. 327 f.] 

On the other hand, common observation does not as a rule 
observe mental traits, but only certain indirect consequences of 
them which it is likely to misinterpret. It observes customs, not 



The Influence of Remote Ancestry or Race 6y 

moral capacity ; habits, not energy ; knowledge, not^ intellect. 
But, obviously, the habits and knowledge possessed by a race 
do not measure its present original nature. Its habits and knowl- 
edge, its "civilization" or "culture" are in the main due to the 
original nature of men long dead and have come to it by train- 
ing. The origination of advances in civilization is a measure of 
ability, but the abilities that have originated them have prob- 
ably been confined to a very few men. A race that originated 
none of them may now possess them all. Even if a race has 
been completely isolated, its civilization has been originated by 
only a few of its members ; and the chance of men of great gifts 
being born is the result not only of the central tendency of a 
race and its variability, but also of its size. Other things be- 
ing equal, there is a far greater chance of the birth of a man 
of great ability in a tribe of a million than in one of a thousand. 
Since one such man may add to the knowledge and improve 
the habits of the entire group regardless of its size, civilization 
will progress more rapidly in large than in small groups, in a 
condition of isolation. 

The civilized races have not remained isolated and have got 
most of their civilization from without. Of ten equally gifted 
races in perfect intercourse each will originate only one tenth 
of what it gets. The original nature of the Germans of to-day is not 
much different from that of their ancestors in the time of Taci- 
tus, and their progress in the meantime is not properly theirs, 
but that of the European world and its American colony, each 
of whose racial stocks has added something to a common fund. 

Again the civilization, — the habits and customs, — of a race 
need not be in a direct proportion to its intellect, even if entirely 
caused by it. A very slight difference in intellect might give 
one real supremacy over another, enable it to condemn the 
other to servitude and so free its own intellect from uninstruct- 
ive labor. It would thenceforth progress in civilization much 
more rapidly than the other. What the mental ability of a race 
actually achieves is due to the conditions under which it oper- 
ates, and a race may put on or put off such conditions or have 
them imposed or removed by other races, for all sorts of reasons. 

From all these facts each student may make his own esti- 
mate of the original mental differences of races, and learn at least 
the need of more actual measurements of race differences and 



68 Educational Psychology 

of intelligence in interpreting them. My own estimate is that 
greater differences will be found in the case of the so-called 
"higher" traits, such as the capacity to associate and to 
analyze, thinking with parts or elements, and originality, than 
in the case of the sensory and sensori-motor traits, but that 
there will still be very great overlapping. Calling the dif- 
ference between the original capacity of the lowest congenital 
idiot and that of the average modern European loo, I should 
expect the average deviation of one pure race* from another 
in original capacity to be below lo and above i, and the dif- 
ference between the central tendencies of the most and the least 
gifted races to be below 50 and above 10. I should consider 3 
and 25 as reasonable guesses for the two differences. 

Even if the differences were far larger than these, the prac- 
tical precept for education would remain unchanged. It is, of 
course, that selection by race of original natures to be educated 
is nowhere nearly as effective as selection of the superior indi- 
viduals regardless of race. There is much overlapping and the 
differences in original nature within the same race are, except 
in extreme cases, many times as great as the differences between 
races as wholes. 

*Defining a pure race arbitrarily as one whose ancestry has less than 
I per cent of community with that of any other race for at least 20 
generations back. 



CHAPTER V 
The Influence of Immediate Ancestry or Family 

There is possibly even less agreement about the amount of 
influence of immediate ancestry or ' family ' than about that of 
remote ancestry or race. This is the more to be regretted because 
all the social sciences and especially education need as a starting 
point precise knowledge of the differences in original mental make- 
up within the human species and of their relation to immediate 
ancestry. 

The problem naturally resolves itself into two, — the measure- 
ment of the resemblance of individuals of like ancestry and the 
subtraction of a proper allowance for their likeness in training. 
Or, more exactly, we have to measure the amount by which the 
likeness of individuals of like ancestry surpasses the likeness 
of individuals of different ancestry, and subtract from it the 
amount due to their greater likeness in training than that 
found in the case of individuals of different ancestry. Measure- 
ments of the greater differences of wwrelated individuals with an 
allowance for the greater differences in their training would serve 
the same end. But the effect of differences in ancestry in pro- 
ducing differences in intellect and character is more easily meas- 
ured by the effect of similarity or identity in ancestry in decreas- 
ing such differences. The facts to be considered are then meas- 
urements of resemblance and allowance for like training. 

The Variability of Individuals of the Same Sex and Ancestry 

Resemblance, not repetition, is to be measured. To say that 
a man's original nature depends upon his ancestry does not mean 
that it is an exact facsimile of any one or any combination of his 
ancestors. There is no reason to believe that four sons of the 
same parents and consequently of the same total ancestry will 
have the same original natures. Indeed we know they will not, 

(60^ 



70 Educational Psychology 

save by chance. For twins who have presumably in some cases 
identical or nearly identical antenatal influences and nurture may 
vary widely in both physical and mental traits. What ancestry 
does is to reduce the variability of the offspring and determine the 
point about which they do vary. 

Take, for instance,' the capacity to form intelligent habits or 
associations amongst sense impressions, ideas and acts. The num- 
ber of associations between situation and act, the number, that 
is, of things an animal can do in response to the multitude of 
conditions of life, varies tremendously throughout the animal 
kingdom. The free swimming protozoa studied by Professor 
Jennings had in addition to the common physiological functions 
hardly more than a single habit. The sum of the life of Para- 
Dioecium is to eat, breathe, digest, form tissues, excrete, reproduce, 
move along in a steady way, and when passing from certain media 
into others to stop, back, turn to the aboral side and move along 
again as before. At the other extreme is a cultivated human being 
whose toilet, table manners, games, speech, reading, business, etc., 
involve hundreds of thousands of associative habits. 

If now we take a thousand descendants of human beings and 
count up the number of associative habits displayed by each we 
shall of course find a great variability. Some of our thousand 
human offspring will learn fewer things than some dogs and 
cats. Some of them may learn many more than any of the 
parents from whom they sprang. But on the whole the offspring 
of human beings will vary about the human average instead of 
about the general animal average, and the average deviation of the 
human group will be far less than that of the whole animal, 
kingdom. 

To illustrate again, the children of parents who are, say, 3 
inches above the average of the general population in stature will 
vary not about the general average, but about a point 2 inches 
above it ; and will differ one from another only about ten seven- 
teenths as much as one adult of the general population differs 
from another.* 

Immediate ancestry will then, when influential, cause children 
to deviate from the general average toward the condition of their 

* This illustration is based on the data reported by Galton in Natural 
Inheritance. 



The Influence of Immediate Ancestry or Family yi 

parents and to vary less among themselves than would the same 
number of unrelated individuals. 

It might seem at first sight that two individuals of the same 
sex, race and parentage, two brothers or two sisters, should, if 
ancestry counted at all, have identical original natures and differ 
only in as far as different environmental forces affect them. 
Common observation shows this to be false, but common thinking 
does not always or often understand that it is false just because 
immediate ancestry does count. If ancestry did not count, either 
all men would by original nature be identical, or the variations 
among them would all be miracles. If ancestry did not count, 
two brothers might well be identical in original nature, for all 
human males might be. But if ancestry is a force, it is certainly, 
a variable one, the germs produced by any one parent being some- 
what different among themselves for the same reason that the 
germs produced by all parents together vary still more. If the 
germs differ at all, the differences are likely to be less amongst 
the germs of any one human being than amongst an equal number 
from all men, but the differences are not at all likely to be reduced 
to zero. 

In all thought of inheritance, physical or mental, one should 
always remember that children spring, not from their parents' 
bodies and minds, but from the germs of those parents. The 
qualities of the germs of a man are what we should know in 
order to prophesy directly the traits of his children. One quality 
these germs surely possess. They are variable. Discarding syn- 
tax and elegance for emphasis, we may say that the germs of a 
six-foot man include some six-feet germs, some six-feet-one 
germs, some six-feet-two, some five-feet-eleven, some five-feet- 
ten, etc. Each human being gives to the future, not himself, but 
a variable group of germs. This hypothesis of the variability of 
the germs explains the fact that short parents may have tall sons ; 
gifted parents, stupid sons ; the same parents, unlike sons. 

Methods of Measuring Resemblance in Mental Traits 

In order to understand the measurements of the resemblance 
of related individuals which are to be reported in this chapter, 
it will be helpful to consider one sample case in some detail. 
Table 8 gives (in columns i and 2) the facts concerning the 
cephalic index (width of head divided by length of head) in the 



72 Educational PsycJwlogy 

case of 78 individuals, comprising 39 pairs of twins. Columns 3 
and 4 give the same facts expressed as deviations from .81, which 
is the central tendency for cephalic index in the population from 
which these children were chosen. That is. the first four columns 
of the first line of the table read, — " Of two twins one had a 
cephalic index of ./SS, the other of .790 ; one was .025 below* 
the average of the population, the other was .023 below it." 

Cohnnn 5 gives the difl"erence between the indices of the twins 
in each of the 39 pairs. Column 6 gives the algebraic product of 
the deviations of the indices of the twins from the average cephalic 
index of the population. 

Consider first column 5, in connection with this question. ** How 
much smaller is the diflference between twin and twin of a pair 
than that between two children in general ? " Colunm 5 gives the 
former differences ; the latter can be got by getting all the dififer- 
ences between each child and the other seventy-seven. Thus we 
find individual 1 differing from loi, 2, 102, 5. 105, 6. 106, etc., 
by 2, 8, 15, 18, 24, 28, 38, 61, 49, etc. Individual loi differs 
from 2, 102, 5, 105, 6, 106, etc., by 10, 13. 16, 22, 26, 36, 59, 47, 
etc. Individual 2 dift"ers from 102, 5, 105, 6, 106. etc., by 7. 16, 
32, 36, 40, etc. The differences between twin and twin range 
from o to 57. averaging 18. If the reader should figure out the 
difference between two children of the same age but not of the 
same family, he would find it to range from o to 174 or more 
and to average about 40. This is the simplest method of meas- 
uring the degree to which individuals of like ancestry resemble 
one another more than individuals of unlike ancestry do. But it 
is for many reasons not the most convenient way and is rarely 
used. 

Consider now columns 3 and 4 in connection with the question, 
" How much oftener are the twins both short-wide-headed or 
both long-narrow-headed than are two children in general ? " 
Both twins are thus alike (that is both deviate from the average 
in the same direction) in 32 out of the 39 pairs, or in 82 per 
cent of the cases. Two children taken at random will be thus 
alike in 50 per cent of the cases. ' Greater th.an ^o f>cr cent fre- 
quency of dcz'iation of related indk'iduals in the same direction 
front the coitral tendency,' is another simple measure of their 
greater resemblance than that of the non-related individuals. 

* Below tneaning more long-narrow-headed, or "dolichocephalic." 



The Influence of Immediate Ancestry or Family 73 

TABLE 8. 
Resemblances of Twins in Cephalic Index. 



Pairs OF ^x °X t zl 2S l'^ g"? 

Twins S S -sS 2| i^ ,5|-5 a 

Bio Oio uiu tfli) " t", « 

^I ^T §" . §" . ^ ^x-s-> 

o u Q P O fe 

1 and loi 788 790 —25 — 23 2 575 

2 " 102 780 773 —33 —40 7 1320 

5 " 105 796 812 — 17 — I 16 17 

6 " 106 816 826 3 13 10 39 

7 " 107 849 837 36 24 8 864 

8 " 108 853 859 40 46 6 1840 

9 " 109 777 766 — 36 — 47 II 1692 

10 " no 801 770 — 12 — 43 31 516 

11 " III 745 738 —68 —75 7 5100 

12 " 112 804 773 — 9 — 40 31 360 

13 " "3 823 859 10 46 36 460 

16 " 116 765 763 — 48 — 50 2 2400 

17 " 117 778 788 —35 —25 10 875 

18 " 118 836 836 23 23 o 529 

19 " 119 839 797 26 — 16 42 .... — 416 

20 " 120 761 768 — 52 — 45 7 2340 

21 " 121 786 783 — 27 — 30 3 810 

23 " 123 806 831 — 7 18 25 .... — 126 

24 " 124 778 784 —35 —29 6 1015 

25 " 125 826 850 13 37 24 481 

26 " 126 802 793 — II — 20 9 220 

27 " 127 834 839 21 26 5 546 

28 " 128 763 817 — 50 4 54 .... — 200 

29 " 129 827 843 13 30 17 390 

30 " 130 814 827 I 14 13 14 

31 " 131 789 773 —24 —40 16 960 

32 " 132 819 828 6 15 9 90 

34 " 134 758 725 —55 —88 33 4840 

35 " 135 817 780 4 —33 37 —132 

36 " 136 786 836 —27 23 50 —621 

37 " 137 817 830 4 17 13 68 

38 " 138 827 846 13 31 18 403 

40 " 140 850 793 37 —20 57 —740 

41 " 141 838 846 25 31 6 775 

43 " 143 783 786 —30 —27 3 810 

44 " 144 785 826 —28 13 41 —364 

45 " 145 899 856 86 43 43 3698 

47 " 147 832 828 18 14 4 252 

50 " 150 836 838 23 25 2 575 



74 Educational Psychology 

Consider now columns 3 and 4 in connection with this ques- 
tion, " What is the ratio of one twin's deviation from the C. T.* 
to that of his mate ? " We find these 78 ratios, using the ratio 
of I's deviation to loi's and also loi's to I's and so on, to be 
If. If. fo. It. V. TT. A. -/. etc., fourteen of them being minus 
quantities. The central tendency (Median) of these ratios is .87. 
Now if twin and twin always possessed perfect resemblance, — 
if the two indices of each pair were alike, — these ratios would 
each be I. If we take the ratio of any person's deviation from 
the C. T. to that of any other person regardless of blood rela- 
tionship, there will be as many minus quantities as plus quantities 
and the median of the ratios will be o. The median of the ratios, 
each of the deviation of one member of a related pair from the 
central tendency of the whole group to the similar deviation of 
the other member, is an important measure of resemblance. 
When it is o, it means no greater resemblance than one of the 
group bears to another taken at random. When it is i.oo it 
means perfect resemblance or identity. When it is .5 it means 
a resemblance halfway between perfect identity and that found 
between any two persons of the group taken at random. This 
is for many reasons the most serviceable measure of resemblance 
between individuals, and it, or a measure that may for the pur- 
poses of this chapter be regarded as the same as it, will be used 
in reporting the resemblances found by various students of hered- 
ity. The figures, ranging from o to i.oo, called Coefficients of 
Correlation, designated by the symbol R, and used to measure 
resemblance, are to be thought of as expressing the central tend- 
encies (medians) of series of ratios, such as the series of 78 ratios 
afforded by the deviation-measures of Table 8. 

The central tendency of a series of ratios may however be cal- 
culated in another form, the so-called Pearson coefficient of cor- 
relation or resemblance, which is somewhat less easy to describe. 
Consider column 6 in connection with the question, "What would 
these products be if the two twins were identical in the case of 
every pair?" In the first pair the product is 575. If the twins 
were identical it would be either 625 (25 times 25) or 529 (23 
times 23) according as the second twin was to be identical with 
the first or the first with the second. In the second pair the 

*C. T. is used here and later as an abbreviation for central tendency. 



The Influence of Immediate Ancestry or Family 75 

product is 1320. With perfect resemblance it would be 1089 or 
1600. In the third pair it is 17. With perfect resemblance it 
would be 189 or i. In the fourth the corresponding products 
are 39 and 9 or 169. In the fifth pair they are 864 and 1296 or 

576. 

Consider now the sum of the five products as it is (2815), and 
as it would be with perfect resemblance (3208 or 2875). Con- 
sider what the sum of the products would be with no greater 
resemblance than that found between any one of the group and 
any other one taken at random. A plus deviation would then go 
with a minus deviation as often as with a plus ; in the long run 
as many of the algebraic products would be negative as positive ; 
and their sum would be o. The proportion which the sum of 
the products of the related deviations is of what that sum would 
be with perfect resemblance is thus a measure of the amount of 
resemblance. 

This proportions ^ 1 y^ + ^^7 , + X aYs x„y„ 

2" X. y 

V i'x2.i'y2 

Xi, Xg, X3, etc. being the deviations of the first members of the 
related pairs, and y 1,72,73, etc. being the corresponding deviations 
of the second members of the related pairs. 2"= * sum of the 
series of. ' 

Thus for the 5 pairs above 

2815 



or 



1 3208.2875 



^x y 
When ' ^ z- = 1, resemblance is perfect. 

1/2x2. Jy^ ^ 

When — ^ -2 ^^ Q? there is no greater resemblance than 

exists between the members of the group taken at random. A 
resemblance calculated by this, the so-called product-moment 
method, devised by Karl Pearson, may for our purposes be con- 
sidered as meaning the same thing as the median of the series of 
ratios previously described. 

If the reader still feels a certain insecurity and unreality about 
the values of R = o, R = .i, R = .2, R = .35, R=.75, R=-9. 
and the like, he can make these coefficients of resemblance or 



76 Educational Psychology 

correlation living realities by artificially so pairing the following 
series as to get from them various values of R, either as R= the 

X V ^X V 

median of the — -| — — ratios or as R — 



y X V Ix\Iy^ 

Series i. (x) + 1 +1 + 1 + 1 +3+3+3 + 5 + 7 + n — i — i- i — i- 

3-3-3-5-7-11 
Series 2. (y) + i + i + i + i+3+3+3+5 + 7 + ii— i — i-i-i — 

3-3-3-5-7-11 
Thus, pairing them in order, R= i, while pairing them 

( + 1+3) ( + 1-1) (+1 + 1) (+1-1) ( + 3+3) ( + 3 + 5) ( + 3-1) 

( + 5 + 1) ( + 7 + 11) ( + 11 + 1) (-1+7) (-1-3) (-1-5) (-1+3) 

(-3 + 1) (-3-1) (-3-7) (-5-11) (-7-3) (-ii-3),R = -54. 
It will be specially useful to pair them so as to get R = — i, so 

as to get R = o, so as to get R = about .2, and so as to get 

R = about .8. 

The Influence of Ancestry on Physical Traits 

Before describing the similarities of closely related individuals 
in mental traits I shall present the results of studies in the case 
of some physical traits which will prove that heredity is a z'cra 
causa, since, in them, similarity of training is out of the question 
as a cause of the similarities found. 

The coefficient of correlation between brothers in the color of 
the eyes is, according to Pearson, .52. But parents could not, if 
they would, exert any environmental influence upon the color of 
•their children's eyes. The fraternal resemblance must be due to 
the resemblance in ancestry. 

In height Pearson finds the coefficient of correlation between 
father and son to be .3, and that between brother and brother to 
be .5. In other words, a son, on the average, deviates from the 
general trend of the population by .3 the amount of his father's 
deviation, a brother by .5 the amount of his brother's. Now no 
one can imagine that tall fathers try especially to make their sons 
tall. Nor will the class ' men two inches above the average 
height ' feed their children any more than men one inch above it. 

The coefficient of fraternal correlation in the case of the 
cephalic index (ratio of width to length of head) is, according to 
Pearson, .49. Here it is utterly incredible that fathers do any- 



The Influence of Immediate Ancestry or Family yy 

thing to their children that would tend to produce in them similar 
indices. 

Finally take color of hair. Fraternal correlation is, according 
to Pearson, .55. Here again home influence could not cause one 
whit of the resemblance. 

Immediate ancestry can and does, apart from any other force, 
cause in whole or in part the abmodality, or deviation from the C. 
T. of his race, of an individual in the case of stature, cephalic 
index and eye color. There is no reason to suppose that the brain 
is less influenced by ancestry than are the tissues that cause 
height, or the shape of the skull bones that causes cephalic index, 
or the deposits of pigment that cause eye color. Immediate 
ancestry is thus a probable cause for original mental nature. And 
when there is doubt as to the choice between it and the environ- 
ment as the cause of differences in mental traits of individuals 
at any age, it must not be forgotten that the influence of the 
latter is, after all, largely a matter of speculation, while the influ- 
ence of ancestry is in physical traits a demonstrated fact. 

Measurements of the Influence of Ancestry on Mental Traits 

Deafness may be considered a physical trait because it is due 
to physical causes, but so are all mental traits. The real dififer- 
ence is that we know more about the causes in the one case than 
in the others. The manifestation and results of deafness are cer- 
tainly mental traits. 

The brother or sister of a person born deaf is found to be 
deaf in 245 cases out of 1,000, almost one case out of four. The 
number of deaf persons amongst 1,000 brothers and sisters of 
hearing individuals is not known exactly, but it is certainly less 
than I, probably much less. That is, a person of the same ances- 
try as a congenitally deaf person is at least 245 (probably many 
more) times as likely to be deaf as a person of the same ancestry 
as a hearing person. The child of two parents both of whom 
were born deaf is at least 259 (probably many more) times as 
likely to be deaf as the child of two hearing parents [Fay, '98, 
p. 49]. In this case, as with the physical traits described, there 
is no reason to impute any efficacy to training. Parents born 
deaf would take pains to prevent deafness in their children. 

Mr. E. L. Earle ['03] measured the spelling abilities of some 



y8 Educational Psychology 

600 children in the St. Xavier school in New York by careful 
tests. As the children in this school commonly enter at a very 
early age, and as the staff and methods of teaching remain very 
constant, we have in the case of the 180 pairs of brothers and 
sisters included in the 600 children closely similar school train- 
ing. Mr. Earle measured the ability of any individual by his 
deviation from the average for his grade and sex and found the 
coefficient of correlation between children of the same family 
to be .50. That is, any individual is on the average 50 per cent 
as much above or below the average for his age and sex as his 
brother or sister. 

Similarities in home training might theoretically account for 
this, but any one experienced in teaching will hesitate to attribute 
much efficacy to such similarities. Bad spellers remain bad 
spellers though their teachers change. Moreover, Dr. J. M. Rice 
in his exhaustive study of spelling ability ['97] found little or 
no relationship between good spelling and any one of the popular 
methods, and little or none between poor spelling and foreign 
parentage. Yet the training of a home where the parents do 
not read or spell the language well must be a home of relatively 
poor training for spelling. Cornman's more careful study of 
spelling ['01] supports the view that ability to spell is little 
influenced by such differences in school or home training as 
commonly exist. 

These facts make it almost certain that immediate ancestry does 
count somewhat in producing the likenesses and differences found 
amongst men in mental traits. In the measurements now to be 
reported, the influence of family training enters as a more prob- 
able alternative cause of the resemblance. I shall in each case 
give the measurement of resemblance made and the allowance 
for likeness in home training suggested by the author. 

The first serious study of the inheritance of mental traits was 
made in the 6o's by Francis Galton and reported in Hereditary 
Genius ['69, '92]. He examined carefully the careers of the 
relatives of 977 men each of whom would rank as one man in 
four thousand for eminent intellectual gifts. They had relatives 
of that degree of eminence as follows: — fathers 89, brothers 114, 
sons 129, all three together 332 ; grandfathers 52, grandsons 37, 
uncles 53, nephews 61, all four together 203. The probable 
numbers of relatives of that degree of eminence for 977 average 



The Influence of Immediate Ancestry or Family 79 

men are as follows : — fathers, brothers, and sons together, i ; 

grandfathers, grandsons, uncles and nephews all together, 3. 
Galton argues that the training due to the possession of eminent 

relatives can not have been the cause of this superior chance of 
eminence in the relatives of gifted literary men and artists. 

He says : "To recapitulate : I have endeavored to show in 
respect to literary and artistic eminence — 

1. That men who are gifted with high abilities — even men of 
class E — easily rise through all the obstacles caused by inferiority 
of social rank. 

2. Countries where there are fewer hindrances than in England, 
to a poor man rising in life, produce a much larger proportion of 
persons of culture, but not of what I call eminent men. (England 
and America are taken as illustration.) 

3. Men who are largely aided by social advantages are unable to 
achieve eminence, unless they are endowed with high natural gifts." 

Galton demonstrates that the adopted sons of popes do not 
approach equality in eminence with the real sons of gifted men. 
He so orders his studies of men eminent in other fields as to leave 
very slight basis for one who argues that training and opportunity 
rather than birth caused the eminence attained. Finally, Gal- 
ton's own opinion, that of an eminently fair scientific man based 
upon an extensive study of individual biographies, may safely be 
taken with a very slight discount. He says : — 'T feel convinced 
that no man can achieve a very high reputation without being 
gifted with very high abilities." 

The historic importance of Galton's Hereditary Genius, the 
originality and ingenuity of its author and its substantial results, 
should make his book the first to be read by every student of 
mental inheritance. 

Loewenfeld ['03] confirms Galton's estimate of the resemblance 
in intellect and energy amongst descendants from similar near 
ancestry. 

In 1889 Galton published his Natural Inheritance, the re- 
sults of more precise studies * of resemblances amongst related 
individuals in stature, eye color, the artistic faculty and diseases. 
He found the resemblance between parents and their children 
in the mental trait studied (artistic faculty) to be a little greater 

*These studies were reported in various memoirs from 1871 to 1887. 



8o Educational Psychology 

than in the case of stature. The essential facts from which this 
inference is drawn are that in 30 families where both parents 
were artistic 64 per cent of the children were so, whereas in 150 
families where neither parent was artistic only 21 per cent of the 
children were so ['89, p. 218]. No attempt is made to divide the 
causation of this resemblance between birth and training. 

Pearson ['04] secured ratings by teachers of about 2,000 pairs 
of siblings with respect to the following traits : — ability, vivacity, 
conscientiousness, popularity, temper, introspection or self-con- 
sciousness, assertiveness and handwriting. In ability and hand- 
writing the measure was a grade from one to six according to 
ability; in temper from one to three. In the other traits the 
individual was put into an upper or a lower class. Such material 
is not well suited for measuring resemblance, chiefly for two 
reasons. First, the measurements are very coarsely made, and 
so have a large chance inaccuracy. A slight prejudice or ignor- 
ance in the teacher making the measurement may put a boy who 
is really above the average in one of these traits below it. If 
errors of judgment displace a boy on the scale at all, they will 
alter his position by half the total scale in five of these traits, by 
a third of the scale in one and by a sixth in the other. Such 
chance errors are sure to occur. Their effect is to make the 
resemblances obtained from the teachers' ratings lozver than the 
real resemblances. Spearman ['04, p. 97 ff.] has estimated that 
if these teachers' ratings suffer from such chance errors as he 
himself finds in such ratings, the obtained resemblances (which 
are about .5) are very much too low, the real resemblances 
required to produce a measurement of R == .5 when ' attenuated ' 
by the teachers' chance errors, being over .8. Pearson denies that 
the teachers' ratings were thus inaccurate, claiming that they 
displaced a pupil from his proper class only rarely. Spearman 
possibly overestimates the chance errors of a teacher's judgment 
of the intellect or character of a boy well known to him, but 
Pearson certainly underestimates them, when he makes no allow- 
ance at all for them. 

He measured them only in the case of ' ability,' which would 
be the easiest of these traits for a teacher to grade accurately, and 
which was graded by a six-step scale. Three teachers in a school 
graded the same pupils for him * without consultation among 

*This being done for some 150 boys and girls in all, distributed in six 
schools. 



The Influence of Immediate Ancestry or Family 8i 



themselves, with the result, he writes, that ' the agreement in 
classification was complete in more than 80 per cent of cases and 
only differed by as much as two classes in about 5 per cent of 
cases.' ['04, p. 161.] But such gradings are not really indepen- 
dent, if the pupils are talked about by their teachers. 



J»- 



Js. 



» 



Fig. 24. The real un- 
likeness of Jo. and Ja. 



Fig. 25. The specious likeness of Jo. and Ja. 
when they are rated by teachers who place'the 
dividing-line between self-conscious and unself- 
conscious too low or too high. 



The second error acts in the reverse direction. Any teacher 
has his own idea of ' quiet,' ' noisy,' ' keen' in conscientiousness 
or ' dull ' in conscientiousness, and the like. Whether he shall 
rate a boy as ' self-conscious ' or ' unself-conscious ' depends only 
in part on what the boy's nature is. In part it depends on where 
the teacher draws the line between being self-conscious and being 
unself-conscious. Suppose, for instance, John and James to be 
really at points lo and la on the scale for self-consciousness 
represented in Fig. 24, and suppose the average self-consciousness 

6 



82 Educational Psychology 

of English boys to be really at point Av. on this scale. Consider 
now ten teachers each of whom is asked, " Is John self-conscious 
or unself-conscious ? " Each of them is in total ignorance of the 
position of the dividing point, every point above which should be 
rated ' self-conscious ' and every point below which should be 
rated ' unself-conscious.' Each of them makes his own dividing 
point. These divisions will vary. How much they will vary is 
not known. Fig. 25 gives an arbitrary estimate of ten as 
an illustration. Now John and James, when rated by these ten 
subjective scales, seem alike in four cases out of ten, though they 
are really not in this sense alike, one being really above and the 
other below the real dividing line. Now, in general, any differ- 
ence in judges in making the subjective divisions of the scales 
whereby they rate the boys will lead the judges to rate boys who 
are really different as alike oftener than it will lead them to 
rate boys who are really alike as different. For there are many 
more boys near the dividing line than at the extremes, and the 
brothers of a pair are usually rated by the same judge. Hence 
the resemblances as calculated from these teachers' ratings are, 
in so far forth, greater than the real resemblances. How much 
greater is not known, since the amount of difference between the 
subjective and the real dividing point is not known. The error 
would probably be greater in the case of conscientiousness, self- 
consciousness and shyness, where subjective standards prob- 
ably vary very much, than in the case of intelligence or popularity. 
The average resemblance of .52 obtained by Pearson would thus 
be raised if one error had been avoided, and lowered if a second 
error had been avoided. I judge that roughly on the whole the 
two errors would somewhat nearly balance. Just what would 
happen to each of the particular resemblances if accurate original 
measurements had been secured, cannot be more than guessed. 
Pearson's obtained measures were ['04, p. 155] : — 









Brother and 


Brothers 


Sisters 


Sister 


Vivacity 
Self-assertiveness 


47 
53 


•43 
•44 


•49 
•52 


Introspection 

Popularity 

Conscientiousness 


59 
50 
59 


•47 
•57 
.64 


•63 
•49 
.63 


Temper 

Ability 

Handwriting 


51 
46 

53 


•49 
•47 
.56 


•51 
•44 
.48 


Average 


52 


.51 


•52 



The Influence of Immediate Ancestry or Family 83 

A third criticism of Professor Pearson's measurements might 
be that the teachers who reported cases of brothers tended to 
select brothers whose Hkeness was notable and to grade them alike 
oftener than the facts warranted. It is true that if you seek 
information from people without special training in the field of 
science concerned, the answers obtained are well-nigh sure to 
be compounds of fact and prejudice, but there is apparently no 
reason to believe that the teachers had, apart from the directions 
sent to them, any prejudicial belief in fraternal similarity. 

In two ways the directions for making the judgments may 
have tended to suggest the existence of resemblances. The 
directions read: — " i. The object of this investigation is two- 
fold : ( I ) To ascertain the degree of resemblance, mental and 

physical, between children of the same parents 

2. The measurements and estimates are to be made on (I) 
Pairs of brothers (white data paper). (II) Pairs of sisters (pink 
data paper). (Ill) Pairs of brothers and sisters (blue data 
paper)." ['04, p. 161.] It would have been far better to have 
had all the children in the school rated each on a sheet by himself 
and to have said nothing about the purpose for which the meas- 
urements were to be used. 

There is one more fact to be noted which must lessen con- 
fidence in these measurements still further. Using just the same 
method of securing the data as in the cases discussed. Professor 
Pearson gets, from ratings of athletic or non-athletic , resemblances 
of .72 for brothers, .75 for sisters and .49 for brother and sister 
['04, p. 154]. Now we know that if these measurements are 
free from error in all respects save the mere chance errors of 
judgment of the teachers, the real resemblances must be even 
higher than .72, .75 and .49. But so close resemblance as a result 
of original nature alone is absurd. There is nothing like it else- 
where in fraternal resemblances, save in twins. In the case of 
athletic power Professor Pearson's figures surely measure the 
differences of schools in devotion to athletics or the differences 
of the judges as to where the dividing line is between athletic 
and not athletic, as well as the resemblances of brothers and 
sisters in original nature. 

Professor Pearson thinks that no allowance is due for the 
similarities of home training because the resemblances in health, 
€ye-color, hair-color and five other physical traits average .54, 



84 Educational Psychology 

.53 and .51 for the three groups of pairs. The resemblances 
in these physical traits cannot be due to the fact that the brothers 
have the same home environment, he says, yet the resemblances 
are as great as in mental traits. Professor Pearson lays great 
stress on the exact equality of physical and mental resemblance, 
but since his measures of the latter are subject to two important 
sources of error, this exact correspondence is of doubtful 
significance. 

Unless one is a blind devotee to the irrepressibility and unmod- 
ifiability of original mental nature, one cannot be contented with 
the hypothesis that a boy's conscientiousness or self-consciousness 
is absolutely uninfluenced by the family training given to him. 
Of intelligence in the sense of ability to get knowledge, rather 
than amount of knowledge got, this might be maintained. But 
to prove that conscientiousness is irrespective of training is to 
prove too much. One fears that Professor Pearson may next 
produce coefficients of correlation to show that the political party 
a man joins, the place where he lives, and the dialect he speaks 
are matters of pure inheritance uninfluenced by family training! 

The reader may at this stage be in some doubt as to precisely 
what Professor Pearson's measurements give as a probable simi- 
larity of brothers' original natures. I share this doubt, and from 
estimating the different sources of error can do no more than 
expect that adequate mental measurements with the effects of 
similarity of training eliminated would leave resemblances of 
from .3 to .5. 

Dr. Frederick Adams Woods has reported in Mental and 
Moral Heredity in Royalty ['06], a work which appeared first in 
the Popular Science Monthly in 1902 and 1903, measurements 
of the resemblances in intellect and in morals of many individuals 
chosen from the royal families of Europe. Dr. Woods gave to 
each person of the 671 studied a rating from i to 10 on a scale 
for intellect — i representing feeble-mindedness or imbecility ; 10 
such gifts as those of William the Silent, Frederick the Great 
and Gustavus Adolphus ; and 2, 3, 4, 5, etc., steps at equal intervals 
between, in his opinion. These ratings represented Dr. Woods*^ 
impressions from reading the statements of historians and biog- 
raphers about these individuals. He gave similar ratings for 
morality. 

The ratings assigned by Dr. Woods are, of course, not accur- 



The Influence of Immediate Ancestry or Family 85 

ate. No one man's ratings of nearly seven hundred historical 
personages could be. The effect of this chance inaccuracy would 
be to make all his measurements of resemblance lower than the 
real resemblance. He may also have erred from an unconscious 
prejudice by rating as too much alike individuals who were closely 
related. This error would tend obviously to make his estimate 
of resemblance too high. His ratings are given in full and so far 
nobody has proved or even suggested that they are thus biased. 

There is still another chance for error. The reputation of a 
prince may be a peculiarly unfair measure of his ability. A son 
whose gifted father has brought the nation's affairs into a pros- 
perous condition may thereby get, in histories and biographies, an 
unduly high rating; whereas a son who must strive against the 
unfavorable conditions produced by a stupid father, may thereby 
incur an undeserved repute of inefficiency. This is, however, no 
more plausible a supposition than the opposite one that a moder- 
ately gifted son would be rated too low by contrast with a gifted 
father and too high if his predecessor had been a marked failure. 
On the whole Dr. Woods' ratings seem little subject to error 
other than chance inaccuracy, so that the resemblances calculated 
from them are probably too low rather than too high. 

The bulk of this work is devoted to the concrete description 
of particular stocks and the consequences of particular matings. 
To Dr. Woods at least the likenesses and differences of these 
men and women seem due in very large measure to their likeness 
and difference in ancestry, not only in the case of the degree of 
intellect and of morals but also in the direction of interests and 
in minor features of temperament. The general results of the 
measurements of resemblance are as follows : — "By taking the 
records of each country separately and analyzing them minutely, 
we have seen how almost perfectly established heredity appears 
to be as a cause of decided mental and moral peculiarities, 
wherever found. Instead of treating each country separately, 
the entire number of interrelated persons will now be studied as 
if they were arranged on a single chart, according to blood rela- 
tionship. If such a great chart were constructed, we should see 
the geniuses, or (9) and (10) grades, not scattered at random 
over its entire surface, but isolated little groups of (9) and (10) 
characters (the individuals within each group contiguous to each 
other) would be found here and there. One such group would 



86 Educational Psychology 

be seen centering around Frederick the Great, another around 
Queen Isabella, of Spain, another in the neighborhood of William 
the Silent, and still a fourth with Gustavus Adolphus as a center 
These would constitute the largest groups of closely related (9) 
and (10) characters. There would also be a few other groups of 
two or three geniuses each. 

" Those in the lowest grades for intellect would also be found 
close to others of the lowest type, and would fall especially in 
Spain and Russia, in which countries we have seen an inherited 
insanity. There would be certain regions composed almost 
entirely of grades from (4) to (7). These would cover the 
greater part of the chart and include the houses of Hanover, 
Saxe-Coburg-Gotha, Reuss, Mecklenburg, Hapsburg in Austria, 
Holstein, Denmark, Saxony, Savoy, Orleans and modern Portu- 
gal." ['06, pp. 265-266.] 

The general tendency to resemblance he finds to be : — 
In intellect : — 

Offspring and fathers, r = .30 ; 

Offspring and grandfathers, r = .16; 

Offspring and great grandfathers, r = .15 
In morals : — 

Offspring and fathers, r = .30 

Offspring and grandfathers, r = .175 
In the case of intellect there is a peculiarity in the resemblance. 
Men of grades i to 4 have equally gifted fathers ; only from 
then on is there a rise in paternal gifts in proportion to the gifts 
of the offspring. In moral qualities it is not so. 

Dr. Woods thinks that little or no allowance need be made for 
greater similarity of environment for son and father or grand- 
father than existed for sons of royal families in general. He 
says that, while educational opportunities have been unequal, the 
"advantages and hindrances must have always been of an acci- 
dental character, depending on various causes, and their distri- 
bution would occur largely at haphazard throughout the entire 
number of collected persons (832) ; and could not account for 
the great group of mediocrity and inferiority, like the houses of 
Hanover, Denmark, Mecklenburg, and latter Spain, Portugal and 
France." ['06, p. 284.] 

So also the advantages of high military or political office have 
been, in his opinion, distributed " at random throughout the entire 



The Influence of Immediate Ancestry or Family 87 

number and could not produce the grouping by close blood rela- 
tionship found throughout this entire study." ['06, p. 285.] 

He tests one environmental influence by the facts, namely, the 
advantage of succession to the throne. " There is one peculiar 
way in which a little more than half of all the males have had 
a considerable advantage over the others in gaining distinction as 
important historical characters. The eldest sons, or if not the 
eldest, those sons to whom the succession has devolved, have 
undoubtedly had greater opportunities to become illustrious than 
those to whom the succession did not fall by right of primo- 
geniture. I think every one must feel that perhaps much of the 
greatness of Frederick II, of Prussia, Gustavus Adolphus, and 
William the Silent, was due to their official position ; but an actual 
mathematical count is entirely opposed to this view. The in- 
heritors of the succession are no more plentiful in the higher 
grades than in the lower. The figures below show the number in 
each grade who came into power by inheriting the throne. 

Grades i 23456789 10 

Total number in each Grade .. . 7 21 41 49 71 70 68 43 18 7 

Succession Inheritors 5 14 26 31 49 38 45 23 8 4 

Percent 71 67 63 64 69 54 67 54 67 57 

It is thus seen that from 54 to 71 per cent inherited the suc- 
cession in the dififerent grades. The upper grades are in no way 
composed of men whose opportunities were enhanced by virtue 
of this high position. Thus we see that a certain very decided 
difference in outward circumstances — namely, the right of suc- 
cession — can be proved to have no effect on intellectual distinc- 
tion, or at least so small as to be unmeasurable without much 
greater data. The younger sons have made neither a poorer nor 
a better showing." ['06, pp. 285-286.] 

His conclusion is :— " The upshot of it all is, that as regards 
intellectual life, environment is a totally inadequate explanation. 
If it explains certain characters in certain instances, it always 
fails to explain as many more ; while heredity not only explains 
all (or at least 90 per cent) of the intellectual side of character 
in practically every instance, but does so best when questions of 
environment are left out of the discussion. Therefore, it would 
seem that we are forced to the conclusion that all these rough 
differences in intellectual activity which are susceptible of grad- 



88 Educational Psychology 

ing on a scale of ten are due lo predetermined differences in the 
primary ,t;vrm-cells." ['o6, p. 286.] 

In the case of the resemblances in morality Dr. Woods is less 
emphatic in denying that any disconnt for similarity in training 
is required. In fact his attitude is not clear. He says, " The 
conclusion seems to be, therefore, that even in the moral side 
of character, inherited tendencies outweigh the effects of sur- 
roimdings, for the reason that, ai)plied to all the characters, hered- 
ity is able to explain almost every one, — there being but a slight 
error from the expected, — while environment will only explain 
a relatively smaller number. I think we can conclude from this 
that in each individual, inheritance plays, in the formation of 
morality, a force greater than 50 per cent. Other considerations 
enable us to go even farther than this. The comparison between 
maternal and paternal grandsires is significant. Offspring 
resemble their maternal grandfathers as much as their paternal, 
llere we test the resemblances under diverse conditions of en- 
vironment, the conditions of heredity remaining the same, yet 
we find no weakening of the latter force. Such a result is sur- 
prising, for it does seem improbable that environment has no 
infiueuce in the determination of temperament, behavior, and 
virtue in general ; anil there is, of course, an ingrained popular 
belief that it has." ['o(>. p. 294.J 

Rut only a i)age later he adds, " All I can say is, that I have 
made several tests to find a measurable inthience of environment 
apart from inheritance, and have failed to find it in this research." 
I '06, p. 295. 1 In discussing the fact that the same stock shows 
both very bad and very good men and women, he says, "It is 
these strong contrasts, more than anything else, that must lead us 
to the conclusion that what we have in Plate 2 [a chart showing 
moral resemblance of offspring and parents, not reprinted here] 
is truly the effect of blood relationship, for environment should 
not cause this distribution. Spain, France, and Russia give us 
most of the degenerates. In these countries the individuals are 
closely associated in blood with insanity, epilepsy, or other psy- 
choses. This is itself a coincidence to be explained by those who 

iloubt that morality is much the result of inheritance 

When strong contrasts are found among the children, we alwa}s 
find strong contrasts among the ancestors." ['06, pp. 290-292.] 

In 1905 the author published a report [Thorndike, 05] of 



The Influence of Immediate Ancestry or Family 89 

measurements of the resemblances of fifty pairs of twins in 
marking A's on a printed page of capital letters (A test), mark- 
ing words containing certain combinations of letters (a-t and r-e), 
marking misspelled words on a sheet containing 100 words (mis- 
spelled word test), addition, multiplication and writing the oppo- 
sites of a set of words.* T quote or summarize the essential facts. 
The resemblances of twins, resemblance meaning any greater 
likeness than would be found in a pair of children of the same 
age and sex picked at random from the school population of New 
York City, are: — 

In the A test R = .69 

In the a-t and r-e tests R==.7i 

In the misspelled word test R = .80 + 

In addition R= .75 

In multiplication R = .84 

In the opposites test R = .90 

There were two possible sources of error in the measurements : — 
namely, (i) the possibly unfair selection of twins and (2) the 
fact that the two members of a pair were commonly tested to- 
gether. The method of discovering twins was as follows: — 
Teachers in certain schools were asked to inquire of their pupils 
whether any one had a twin brother or sister. All twins so 
reported were tested. But also frequently some teachers would 
report that in such and such a school there was a pair of twins. 
These could then be found quickly and measured. These reported 
cases were perhaps likely to have been noticed in the first case 
because of their likeness and so to be an unfair selection. Again, 
in the New York schools it is usual to separate the sexes after 
three or four years of school life, and it is a frequent practice 
to separate them from the start. Twins of like sex are therefore 
more conveniently obtained and so more often tested than their 
general frequency would recommend. The amount of the result- 
ing constant error is not, however, great. f The tests were all 
made by the same individual and in the same way except for 

*Thcse tests are more exactly described in Appendix II. 

fOf the fifty pairs of twins measured there were three more of the same 
sex than would be expected in a random selection. 



go Educational Psychology 

unconscious changes. However, in respect to time of day, con- 
ditions of weather and light, and such conditions as are deter- 
mined by family life, e. g., the lack of breakfast, fatigue from a 
party the previous night, and the like, two twins would, when 
measured at the same time, be influenced alike. Thus the obtained 
resemblance would be too large. I can evaluate the amount of the 
resultant constant error only from general considerations. I be- 
lieve it to be small. This constant error would also influence 
the correction made from attenuation, but here would make the 
obtained resemblance too small. An allowance was made for 
these two sources of error to the best of the author's ability. 

If now these resemblances are due to the fact that the two mem- 
bers of any twin pair are treated alike at home, have the same 
parental models, attend the same school and are subject in general 
to closely similar environmental conditions, then ( i ) twins should, 
up to the age of leaving home, grow more and more alike, and in 
our measurements the twins 13 and 14 years old should be much 
more alike than those 9 and 10 years old. Again, (2) if similarity 
in training is the cause of similarity in mental traits, ordinary 
fraternal pairs not over four or five years apart in age should show 
a resemblance somewhat nearly as great as twin pairs, for the home 
and school conditions of a pair of the former will not be much less 
similar than those of a pair of the latter. Again, (3) if training 
is the cause, twins should show greater resemblance in the case of 
traits much subject to training, such as ability in addition or in 
multiplication, than in traits less subject to training, such as quick- 
ness in marking off the A's on a sheet of printed capitals, or in 
writing the opposites of words. 

On the other hand, (i) the nearer the resemblance of young 
twins comes to equaling that of old, (2) the greater the superiority 
of twin resemblance to ordinary fraternal resemblance is, and (3) 
the nearer twin resemblance in relatively untrained capacities 
comes to equaling that in capacities at which the home and school 
direct their attention, the more must the resemblances found be 
attributed to inborn traits. 

The older twins show no closer resemblance than the younger 
twins, and the chances are surely four to one that with an infinite 
number of twins tested the 12-14-year-olds would not show a 
resemblance .15 greater than the 9-1 1 -year-olds. The facts are: — 



The Influence of Immediate Ancestry or Family 91 

The resemblances of young and old twins compared 

Twins 9-1 1 Twins 12-14 

i) A test 66 73 

2) a-t and r-e tests 81 62 

3) Misspelled word test 76 74 

4) Addition 90 54 

5) Multiplication 91 69 

6) Opposites 96 88 

Averages 83 70 

I have measured the resemblances between sibHngs (children 
of the same parents) a few years apart in age only imperfectly, 
and only in the A test, a-t test and opposites tests. The resem- 
blances are between .3 and .4, or less than half the resemblance 
found for twins. 

The variations in the closeness of resemblance of the twins in 
the different traits show little, and possibly no, direct correlation 
with the amount of opportunity for environmental influences. The 
traits most subject to training- (addition and multiplication) do 
show closer resemblances than the traits least subject to training 
(the A, a-t and r-e test) ; but on the other hand show less close 
resemblances than the traits moderately subject to training (the 
misspelled word test and opposites test). (See page 89.) 

The facts then are easily, simply and completely explained by 
one simple hypothesis : namely, that the natures of the germ 
cells — the conditions of conception — cause whatever similarities 
and differences exist in the original natures of men, that these 
conditions influence body and mind equally, and that in life the 
differences in modification of body and mind produced by such 
differences as obtain between the environments of present-day 
New York City public school children are slight. 

We must be careful, however, not to confvise two totally dif- 
ferent things : ( i ) the power of the environment, — for instance, 
of schools, laws, books and social ideals, — to produce differences 
in the relative achievements of men, and (2) the power of the 
environment to produce differences in absolute achievement. It 
has been shown that the relative differences in certain mental 
traits which were found in these one hundred children are due 
almost entirely to differences in ancestry, not in training ; but this 
does not in the least deny that better methods of training might 
improve all their achievements fifty per cent or that the absence 



92 Educational Psychology 

of training-, say, in spelling and arithmetic, might decrease the 
corresponding achievements to zero. 

Tlie argument is Hmited entirely to the causes which make one 
person ditTer from another in mental achievements under tJie same 
general conditions of life at the beginning of the tzventicth century 
in Au-w ]'ork City as pupils in its scliool sysfon. If the 
resemblance of twins had been measured in the case of a group 
made up partly of New York City school children and partly of 
children of equal capacity brought up in the wilds of Africa, the 
variability of the group in addition and multiplication would have 
increased and the correlation coefficients would rise. They would 
then measure the influence of original nature plus the now much 
increased influence of the environment. 

Heymans and Wiersma ['06 and '07 J sought to measure the 
influence of heredity by having the parents and children in a 
family rated by some one who knew them well. Such reports 
were obtained from physicians through a questionnaire. The 
ratings were under ninety rubrics of which the following are 
samples : — 

1. Is the person in question active (gesticulating, jumping up 
from the chair, going up and down the room) or passive and 
quiet ? 

2. Is the person in question, in his professional, business, school 
or home life, always zealous at his work, or only sometimes 
zealous, or outright lazy? 

The resulting ratings suffer from the constant error toward too 
great resemblance due to the fact that any one family is judged 
with reference to the same dividing line for a trait, the line 
being in a diflferent place along the scale for each judge. This 
source of error is even more mischievous here than in Pearson's 
study, since here apparently one judge commonly rated only one 
family. They also suffer from the random inaccuracy of the 
judgments which, as was shown on page So. would make the 
obtained resemblances too low. 

The authors do not measure the resemblances in the usual way 
nor give data permitting anyone else to do so. In view of the 
insecurity of their original data it seems best not to enter upon 
an explanation of their somewhat awkward method of measuring 
the force of heredity, and not to repeat the figures which are got by 
this method. The authors do not attempt to estimate an allow- 



The Influence of Immediate Ancestry or Family 93 

aiice for the influence of similarity in home training, though they 
state that some such allowance must be made. 

They point out, however, that there is reason to believe that 
the influence of heredity far outweighs the influence of home 
training, since the resemblance is hardly any greater in traits 
much subject to the latter influence than in traits little subject to it. 
They instance industry, sympathy and patriotism on the one hand 
and emotionality, consolability, and memory on the other. 

The Speciali::ation of the Influence of Near Ancestry 

In the facts so far given in this chapter, the emphasis has been 
upon the amount of influence of near ancestry. The degree to 
which it is specialized is also of importance. How far, for 
example, do particular talents exist in a man's original nature as 
a result of his ancestry? Is a man from the beginning organized 
to be a novelist, or only to be a writer of fiction, or only to be an 
artist of some sort, or perhaps even only to be a man of ability? 
How far is this original specialization, if it exists, due to 
ancestry? It is a plausible statement that individual minds are 
dependent on heredity only in their rough outlines, the currents 
of mental activity being fixed only in their general directions and 
left to take what particular channels circumstances may decide. 
But this or any other opposite statement must be put in terms 
of ' how much ', ' how far ', ' in what cases ', to be theoretically 
satisfying or practically useful. 

Galton, who had this problem clearly in mind, notes a number 
of relevant facts, some of which I quote. Concerning the judges 
of England between 1660 and 1865 he says: "Do the judges 
often have sons who succeed in the same career, where success 
would have been impossible if they had not been gifted with the 
special qualities of their fathers? . . . 

" Out of the 286 judges, more than one in every nine of them 
have been either father, son or brother to another judge, and 
the other high legal relationships have been even more numerous. 
There cannot, then, remain a doubt but that the peculiar type 
of ability that is necessary to a judge is often transmitted by 
descent." ['69, '92, pp. 61 and 62.] 

Concerning the eminent relatives of eminent statesmen he 
says : " Thirdly, the statesman's type of ability is largely trans- 
mitted or inherited. It would be tedious to count the instances 



94 Educational Psychology 

in favour. Those to the contrary are Disraeh, Sir P. Francis (who 
was hardly a statesman, but rather a bitter controversiaUst) and 
Horner. In all the other 35 or 36 cases in my appendix, one or 
more statesmen will be found among their eminent relations. In 
other words, the combination of high intellectual gifts, tact in 
dealing with men, power of expression in debate, and ability to 
endure exceedingly hard work, is hereditary." ['69, '92, pp. 103 
and 104.] 

Similar specialization of inheritance is shown to be the case 
with the relatives of great commanders, literary men, poets and 
divines. With men of science the fact is much more pronounced, 
twenty-two out of the twenty-six eminent sons of eminent scientific 
men having been eminent in science. This extreme specialization 
of resemblance is in part due, Galton thinks, to training. 

The eminent relatives of eminent painters seem to be well- 
nigh universally gifted in the same special line. In Galton's list 
all the relatives mentioned are painters save four. These were 
gifted in sculpture (2), music (i) and embroidery (i). Finally, 
" Mendelssohn and Meyerbeer are the only musicians in my list 
whose eminent kinsmen have achieved their success in other 
careers than that of music." ['69, '92, p. 231.] 

Of course there is, in the case of all of Galton's facts, the 
possibility that home surroundings decided the special direction 
which genius took, that really original nature is organized only 
along broad lines. Moreover, it is difficult to see just what in the 
nervous system could correspond to a specialized original capacity, 
say, to be a judge. Still the latter matter is a question of fact, 
and of the former issue Galton's studies make him the best judge. 
We should note also that it is precisely in the traits the least 
amenable to environmental influence, such as musical ability, that 
the specialization of family resemblance is most marked. 

Ellis notes ' a clearly visible tendency for certain kinds of ability 
to fall into certain [family] groups.' ['04, p. 83.] In his group 
of 1030 eminent men he finds that, " Men of letters are yielded 
by every class, perhaps especially by the clergy, but Shakespeare, 
and it is probable Milton, belonged to the families of yeomen. The 
sons of lawyers, one notes, even to a greater extent than the 
eminent men of " upper class " birth, eventually find themselves 
in the House of Lords, and not always as lawyers. The two 
groups of Army and Medicine are numerically close together, but 



The Influence of Immediate Ancestry or Family 95 

in other respects very unlike. The sons of army men form a very 
briUiant and versatile group, and include a large proportion of 
great soldiers ; the sons of doctors do not show a single eminent 
doctor, and if it were not for the presence of two men of the 
very first rank — Darwin and Landor — they would constitute a 
comparatively mediocre group. 

"Painters and sculptors constitute a group which appears to be 
of very distinct interest from the point of view of occupational 
heredity. In social origin, it may be noted, the group differs 
strikingly in constitution from the general body, in which the 
upper class is almost or quite predominant. Of 63 painters and 
sculptors of definitely known origin, only two can be placed in 
the aristocratic division. Of the remainder 7 are the sons of 
artists, 22 the sons of craftsmen, leaving only 32 for all other 
occupations, which are mainly of lower middle class character, 
and in many cases trades that are very closely allied to crafts. 
Even, however, when we omit the trades as well as the cases in 
which the fathers were artists, we find a very notable predominance 
of craftsmen in the parentage of painters, to such an extent indeed 
that while craftsmen only constitute 9.2 per cent among the 
fathers of our eminent persons generally, they constitute nearly 
35 per cent among the fathers of the painters and sculptors. It is 
difficult to avoid the conclusion that there is a real connection 
between the father's aptitude for craftsmanship and the son's 
aptitude for art. 

"To suppose that environment adequately accounts for this 
relationship is an inadmissible theory. The association between 
the craft of builder, carpenter, tanner, jeweller, watchmaker, wood- 
carver, rope maker, etc., and the painter's art is small at the best, 
and in most cases non-existent." ['04, pp. 84, 85.] 

Ellis adds, " It may be noted that Arreat {Psychologic du 
Peintre, 1892, ch. 11) in investigating the heredity of 200 eminent 
European painters, reached results that are closely similar to 
those I have reached in my smaller purely British group. He 
found that very few were of upper class social rank, and those 
not usually among the most important, while nearly two-thirds of 
the whole number were found to be the sons either of painters 
or of workers in some art or craft. He refers to the special 
frequency of jewellers among the fathers. I may remark that in 
my list, working jewellers and watchmakers occurred twice, a 



96 Educational Psychology 

small number, but relatively large considering that there are only 
three fathers of this occupation in the total parentage of British 
men of ability." ['04, p. 85.] 

Pearson's measurements concern somewhat specialized traits 
from the start. In so far as his results are trustworthy they 
show equal resemblance in so specialized a trait as temper or hand- 
writing with that found for ' ability.' Woods notes the inheritance 
of literary ability, of common sense, of insanity and other some- 
what specialized traits in the royal families. In the twins whom 
I measured the resemblance is almost or quite as great in the case 
of any one of the six tests (see p. 89) as in the average ability 
in all of them. 

From the work of Burris ['03], if his results are properly 
corrected for the chance inaccuracies in the original measures, it 
would appear that the ability to do well in some one high school 
study is nearly or quite as much due to ancestry as is the ability 
to do well in the course as a whole. 

What knowledge we have thus supports the view that a man's 
original nature is organized by inheritance in great detail, 
particular traits and complexes of traits showing similarity be- 
tween father and son or brother and brother. 

Mental inheritance is specialized also in the further sense that 
two individuals alike in one trait as a result of heredity need not 
be equally alike in some other trait, though the latter be in general 
equally subject to inheritance. For example, a pair of twins 
may be indistinguishable in eye color and stature but notably 
different in hair color and in tests of intellect. 

To measure the extent of this specialization of resemblance, 
exact measures of the resemblance of individual relatives are 
needed. The procedure required to measure accurately the 
resemblance between one individual and another in one trait is 
somewhat intricate, and I shall not describe it here. The reader 
may verify the accuracy of the measures which I give by examin- 
ing Measurements of Twins, [Thorndike, '05] sections 16 to 18 
and 21 to 23. Here I shall simply give the resemblances in 
efficiency in the A test, a-t test, and misspelled word test of the 
ten pairs of twins who showed the closest resemblance in efficiency 
in addition, multiplication, and writing opposites. These show 
(Table 9) that very close resemblance in efficiency in ' association ' 
may go with actual antagonism, or greater unlikeness than that 



The Influence of Immediate Ancestry or Family 97 

shown by children of the same age, taken at random, in efficiency 
in tests of ' perception.' 

TABLE 9. 
Specialization op Resemblance in Twins. 
Resemblance in association : Resemblance in perception : 



Twin 


pair 


resemblance in efficiency 

in add., mult, and oppos. 

combined. 


resemblance in A test, 

word test and misspelled 

word test combined. 


2 


102 




1 .00 — 




.28 


17 


117 




•99 




•83 


20 


120 




1 .00 — 




— .88 


21 


121 




•99 




— .86 


26 


126 




■95 




1 .00 — 


27 


127 




.94— 




1 .00 — 


33 


133 




■95 




1 .00 — 


36 


136 




•94 




— •73 


46 


146 




1 .00 — 




— .98 


48 


148 




1 .00 — 




•97 



In the Measurements of Twins I have also shown in detail that 
twins may be indistinguishable in any one physical trait without 
being at all similar in certain others, or in certain mental traits. 
For example, a pair of twins may show resemblance of .95 to i.oo 
in bodily measurements other than head measurements and of o in 
head measurements. 

As a consequence of the specialization of resemblance the fact 
of ' a child resembling his parents ' is seen to be in reality 'the 
mental traits of a child resembling each the corresponding mental 
trait in his parents.' Each trait or ' character ' may be inherited 
in more or less independence of other traits or ' characters.' 

The Analysis of Mental Inheritance 

It has been noted that the fundamental fact in mental inheritance 
is the relation between the germ making the parent and the germ 
making the child, not between the parent and child themselves. 
It has also been noted that inheritance is not merely of total 
natures vaguely, but of particular details, traits of ' character ' 
each more or less independently of the rest. So far as mental 
traits are thus inherited, we have to think of each amount of each 
trait as possessing some determiner in the germs and of the deter- 
miners of any one trait in different generations of germs as 
standing in some relation. 

7 



98 Educational Psychology 

What is called Mendelism or Mendelian inheritance (after its 
discoverer, Gregor Mendel) offers an account of certain features 
of these determiners and of the relations in which determiners 
of the same trait in successive generations of a family stand. 

In its clearest and most unlimited form* this account would 
state that : — 

First. — The determiner perpetuates itself with little or no vari- 
ation. No such differences exist between the determiners of 
trait A in germ generation i and the determiners of trait A in 
germ generation 2, as are found between parents and children. 

Second. — One fertilized ovum has either (i) no determiner for 
trait A (when neither germ nor ovum had one), or (2) a single 
determiner (when either the germ alone or the ovum alone had 
one) or a double determiner (when both germ and ovum had one). 

Third. — The germ cells later developing from one fertilized 
ovum will in these three cases respectively be (i) all witliout the 
determiner, or (2) half with it and half without it, or (3) all 
with it. 

Fourth. — Any difference between one man and another in 
original nature is reducible to the presence or absence of such 
determiners. Variation in them or blends of one with another are 
not required. 

Fifth. — A ' character ' or trait or feature of an individual may 
be a unit character or a multiple character. A unit character is 
one which is caused by the presence of one single or double deter- 
miner in the fertilized ovum from which the individual developed 
(positive unit character), or by the absence of one single or 
double determiner (negative unit character). A multiple character 
is one caused (i) by the presence of determiners of more than 
one sort, or (2) by the absence of determiners of more than one 
sort, or (3) by the presence of one or more and the absence of 
one or more of a different sort. 

These laws may be illustrated as follows : Call the condition 
of a character, say A, in the individual which is produced by a 
single determiner in the fertilized ovum from which he springs, 
A simplex. Call the condition of the corresponding character in 

*There are other possible views of the implications of the Mendelian 
results with respect to the nature of the determiners, their behavior and 
their relations to the ' characters ' that result from them. There are als^o 
other views of the universality of the laws given here. 



The Influence of Immediate Ancestry or Family 99 



the individual which is produced by a double determiner in the 
fertilized ovum, A duplex. 

Suppose cooperativeness to be a positive unit character. Call 
it C, and call its determiner c. Then the condition in the parents 
may be: — (i) both with C duplex, (2) one with C duplex and one 
with C simplex, (3) both with C simplex, (4) one with C duplex 
and one without C, (5) one with C simplex and one without C, 
(6) both without C. The results will be as follows : 

(i) Ifsall ova have c and all \ / the unions will have \ / and the offspring 
sperms have c J \ 2c / t will have C duplex. 



(2) If all ova have c and half 

of the sperms have c, 

or 

if half of the ova have c 

and all sperms have c 



(3) If half of the ova have c 
and half of the sperms 
have c 



(4) If all ova have c and no 

sperms have c 
or 
if all sperms have c and 
no ova have c 

(5) If half of the ova have c 

and no sperms have c 
or 
if none of the ova have c 
and half of the sperms 
have c 

(6) If no ova have c and no 

sperms have c 



half of the unions 1 / and the offspring 
will have 2c J \ will have C duplex. 

half of the unions \ / and the offspring 
will have I c / \ will have C simplex. 

one-fourth of the un- 1 / and the offspring 
ions will have 2c J | will have C duplex. 



one-half of the un- 
ions will have ic 

one-fourth of the un- 
ions will have no c 



■ the unions will have 

IC 

half of the unions 
will have ic 

half of the unions 
will have no c 



none of the unions \ 
will have c J 



/ and the offspring 
\ will have C simplex. 

/ and the offspring 
\ will have no C. 



/ and the offspring 
\ will have C simplex. 

r and the offspring 
\ will have C simplex. 

/ and the offspring 
\ will have no C. 

/ and none of the off- 
\ spring will have C. 



These results seem at first sight in sharp contrast with the so 
common fact of blended inheritance. Blended inheritance denotes 
the appearance, in offspring from parents possessing A and B 

A -j- B 

respectively, of conditions tending toward , these conditions 

varying amongst the offspring around one central tendency and 
not falling at all into two or three distinct groups. But the gross 
facts of blended inheritance in a trait could perfectly well come 
by the action of the strict Mendelian laws if the trait depended 
on a sufficiently large number of different determiners. 

It is interesting to see the resulting gradations if two, three, 
four, and more determiners produce each an amount of the same 



lOO 



E ducatio nal Psy cho logy 



mental trait. Suppose, for example, that a, b, and c are deter- 
miners of intellect, aa, bb, and cc being the normal double 
determiners. Suppose aa to produce in the individual an amount 
of intellect represented by 2q, bb to produce an amount represented 
by 4q, and cc to produce an amount represented by 8q. Suppose 
a, b, and c to produce each approximately half as much as aa, 
bb, and cc, respectively. 

The union of a germ and ovum could have : — 

o giving o degrees of intellect in the individual, 



or 


a 




iq 




b 




2q 




c 




4q 




aa 




2q 




ab 




3q 




ac 




5q 




bb 




4q 




be 




6q 




cc 




8q 




aab 




4q 




aac 




6q 




aab 




5q 



or any one of many other combinations of the determiners, such 
as aabbcc, aabbc, abbe, etc. The resulting degrees of intellect 
would vary from o to I4q by steps of one. 

The offspring of two individuals would then commonly show 
with respect to intellect as a whole a great variety of degrees 
as in blended inheritance, though the result with respect to the 
effect of any one determiner followed pure Mendelian principles. 
For example, suppose one individual to possess the character due 
to a, duplex ; that due to c, simplex ; and to lack that due to b. 
His intellect will be 6. Suppose another to possess the character 
due to a, simplex ; that due to c, duplex ; and that due to b, 
simplex. His intellect will be ii. On Mendelian principles the 
germs of the first individual will comprise germs with a and c 
and germs with a alone. The germs of the second individual 
will comprise germs with a, c, and b, germs with a and c, and 
germs with b and c. The unions will comprise ac + acb, ac + ac, 
ac + be, a + acb, a + ac, and a + be. The resulting intellects will 
comprise degrees 12, 10, 1 1, 8, 6, and 7. Mendelian principles applied. 



The Influence of Immediate Ancestry or Family loi 

to the elementary factors of heredity might then give, with respect 
to the total traits compounded of these factors, a continuous 
gradation and all the complexities of mental inheritance that 
observation finds. 

Many features of animals and plants have been more or less 
perfectly analyzed into their unit characters, and the determiners 
of these have been got under control in breeding, so that strains 
with a desirable determiner present in all the germs have been 
established. Undesired determiners have been weeded out of all 
the germs of certain individuals, so that the offspring from any 
two of these individuals are sure to be free of the undesired 
character. 

The Mendelian ideal is to represent all of each man's original 
nature by a list of unit characters, to refer each of these to its 
determiner, and to determine the future of the race by arranging 
selection and elimination of the determiners. This ideal is, in 
almost all ways, a great advance over the older plan of represent- 
ing each man by a list of qualities chosen largely by historical 
accidents, referring these vaguely to the germ plasm, and seeking 
to determine the race's future by selection and elimination of 
individuals. 

In one respect, however, it may not be better. This concerns 
its insistence on the invariability of the determiners from genera- 
tion to generation, and within each fraternity of germs. If this 
invariability is perfect, any unit character can appear in only 
two forms or degrees, one corresponding to the presence of a 
double determiner in the united sperm and ovum whence the 
individual developed, and one corresponding to the presence of a 
single determiner. But if this requirement is made strictly, it is 
hard to find any unit characters. Curliness of hair and brownness 
of eye, for instance, seem to be far from constant. The former 
may be separated fairly clearly from straightness,* but within its 
own range it varies from waviness to extreme kinkiness. 

As a result of the difficulty of finding any traits appearing in 
only two degrees each substantially invariable, many students of 
heredity would frankly admit that the determiners did vary some- 
what and that one determiner could blend with another similar 
determiner. 

*Though even this may be doubted. 



102 Educational Psychology 

Mendelian Inheritance in the Case of Intellectual and Moral Traits 

The possibility of analyzing mental traits into unit characters 
and controlling their appearance in the human species by breeding 
so as to get the determiners of desired traits established in all 
the germs, and to get all the germs freed from the determiners 
of undesired ones, is very attractive. If bad temper in man is 
as simple a compound of unit characters as hornedness in cattle or 
color in mice, we may hope to raise a race of assuredly good- 
tempered men! 

It has been suggested [Davenport 'lo, p. I4f.] that imbecility 
is a unit character, depending on the absence of a certain deter- 
miner. " That imbecility is due to the absence of some definite 
simple factor is indicated by the simplicity of its method of inherit- 
ance. Two imbecile parents, whether related or not, have only 
imbecile offspring. Barr gives us such data as the following from 
his experience. A feeble-minded man of 38 has a delicate wife 
who in 20 years has borne him 19 defective children. A feeble- 
minded epileptic mother and an irresponsible father have 7 idiotic 
and imbecile children. The L. family numbers 7 persons, both 
parents and all 5 children imbecile. Among the " Family 
Records " I have been collecting there occurs the R. family where 
A (insane) marries in succession two mentally weak wives and 

has 13 children, all mentally weak In a case 

described by Bennett, a defective father and an imbecile mother 
have 7 children all more or less mentally and morally defective. 
There is, so far as I am aware, no case on record where two 
imbecile parents have produced a normal child." 

I fear, however, that the inheritance of imbecility will be found 
by no means so simple as Dr. Davenport hopes. If it were due 
to the absence of some definite simple factor, there should be 
some clear division of intellects into those from germs totally 
lacking this determiner, those from germs having a single deter- 
miner, and those from germs having the normal double determiner. 
There is certainly no such clear division and it is very doubtful 
if there is any greater division between imbecile and not quite 
imbecile, than between the latter and an intellect a trifle higher, 
and so on up to and beyond individuals of average intellect. The 
condition of the children in the families mentioned above should 
certainly be made the subject of very careful measurements before 



The Influence of Immediate Ancestry or Family 103 

it is assumed that they are all sharply distinct from the offspring 
of parents whose germs possess the ' intelligence ' determiner. 
Rough estimates are very unsafe. 

It seems probable that two imbecile parents produce widely 
varying offspring including some more imbecile than they and 
some far higher than they on the intellectual scale. Richardson 
['02, p. 9] writes: "Imbeciles who have been impregnated by 
imbeciles have produced normal children as a rule in the few 
cases recorded, and in my experience I know of a case where a 
feeble-minded boy of eighteen impregnated a feeble-minded girl 
of sixteen, producing a perfectly normal child." 

Mental traits are certainly not as a rule unit characters or the 
results, each of two or three cooperating unit characters. On the 
contrary, most of them seem to be the results of very manv unit 
characters. It will be shown in Chapter VIII that no case is 
known of a mental trait appearing in three sharply defined degrees, 
— o, moderate, and full amount, — with clear gaps between, 
as a unit character should. Almost, if not quite, all mental traits, 
so far as they are due to original nature, appear in many different 
degrees, each varying very slightly from the next. But this 
gradation in a trait's amount necessitates the existence of many 
determiners to produce it, if it is to be produced by determiners 
that do not themselves vary greatly in force. So, for intellectual 
and moral traits, the task of analysis into unit characters and 
attribution to invariable determiners seems likely to be very, very 
difficult. 

It is not necessary to decide whether the facts of mental inherit- 
ance can be explained by constant determiners or require variable 
determiners ; nor whether, if the latter be the case, two variable 
determiners of the same trait may blend. The question must be 
left for investigation by students from both sides. The chief 
present value of the Mendelian facts and hypotheses to students 
of intellectual and moral traits is as an encouragement to the 
more exact description and analysis of the original natures of 
individual men, and to more exact measurements of individual 
resemblances. 



CHAPTER VI 
The Influence of Maturity 

No competent student doubts that in certain mental traits 
maturity or inner mental growth causes one individual to dififer 
year by year from his former self, irrespective of all training. 
The same force necessarily accounts for some of the differences 
found between children of different degrees of mental maturity. 
If by a miracle a hundred children could be found who were alike 
in sex, ancestry and training, but who were divided into two 
groups by a difference in the extent to which the original impetus 
to mental development had run its course, the groups would differ, 
in at least certain traits, in accordance with this dift'erence in 
stage of growth or maturity. 

About the magnitude of the influence of maturity there is, 
however, a wide range of opinion, from that which would expect 
children in the same stage of growth to be all closely alike and 
all very different from children in a later stage of growth, regard- 
less of differences in their ancestry and training, to that which 
would expect children of the same ancestry and training to be 
all very much alike, regardless of differences in stage of growth. 

The study of the facts is made difficult by the absence of any 
exact measure of maturity, that is, of the extent to which the 
original impetus to mental development has run its course. Length 
of life is the measure which has been used, but chronological 
age is not identical with physiological maturity and neither of 
these two is identical with mental maturity. An individual's 
degree of mental maturity cannot be inferred from his age. In 
the long run, however, the central tendencies of children of the 
ages 6, 7, 8, etc., will represent the central tendencies of 
successive stages in mental growth. And in any case such 
comparisons of children at different ages are the only measure- 
ments available in support of conclusions about the influence of 
maturity. 

(104) 



The Influence of Maturity 105 

Changes in Mental Traits zvith Age 

Some of the best known and most commended studies in 
educational psychology deal with the differences in mental traits 
between children of different ages. The most extensive and also 
the most painstaking study of this sort is Dr. Gilbert's Researches 
on the Physical and Mental Development of School Children 
['94]. A fairly careful examination of its method and results 
will be our best introduction to the general problems of the chapter. 

Dr. Gilbert made a number of measurements of both physical 
and mental traits in boys and girls from six to seventeen years old. 
The mental traits were : 

1. Delicacy of discrimination of weight ('Muscle-Sense'). 
(Ten weights, identical in shape and size, but weighing 84 grams, 
86 grams, etc., were set before a child and he was asked to sort 
out all those which seemed to him to be of exactly the same weight 
as the 82-gram one (which was marked by a white dot). Delicacy 
of discrimination was then measured inversely by the difference in 
weight of the weights thought to be identical.) 

2. Delicacy of discrimination of color. (A series of reds varying 
progressively in darkness were used as the weights were in i.) 

3. Force of suggestion. ( Measured by the amount a child over- 
estimated a weight small in size compared with the same weight 
made much larger.) 

4. Voluntary motor ability. (The number of taps made with 
the finger in 45 seconds.) 

5. Fatigue. (Let T= the number of taps made in the first 
5 seconds of a trial for 45 seconds. Let L = the number of taps 

f L 

made in the last 5 seconds. Let F = — wr~- F was the measure 

of fatigue used.) 

6. Reaction time. (Measured by the time taken to see a signal 
and react by pressing down a key.) 

7. Reaction with discrimination and choice. (Measured by the 
time taken to see that the signal was blue and not red and to react 
by pressing down a key.) 

The essential results of Gilbert's study are given in Table 10. 
It tells with fair accuracy the median ability of every such group 
as ' girls from 9 years o months to 9 years 1 1 months inclusive,' 
and the variability of every such group in four of the traits 



io6 Educational Psychology 

measured. In three traits the variability is given only for boys and 
girls together. 

TABLE lo. 

The Central Tendencies and Variabilities of Children op Dif- 
ferent Ages in Discrimination of Weight, Discrimination of Shades 
OF Red, Resistance to the Size-Weight Illusion, etc. 

M. V. = in all cases the average deviation of the individual children from 
the median child of that year-age. 

B = in all cases, boys. 

G = in all cases, girls. 

D wt. •= the number of grams difference required in order that the 
median child should perceive the difference. 

D col. = the smallest number of differences (not objectively defined) 
required in order that the median child should perceive the difference. 
For a statement of the nature of the differences see Gilbert, '93, p. 42 f. 

H ~ the median difference in grams between the two weights (of equal 
size) chosen as equal respectively to two blocks, each weighing 55 grams 
and being 2.8 cm. thick, but being 2.2 cm. and 8.2 cm. in diameter. 

T = the number of taps made in the first 5 seconds of 45 by the median 
child. 

T-L 

F- /jK (L being tlic number of taps made in the last 5 seconds of 

45 by the median child). 

Rs = thc time, in thousandtlis of a second, between the movement of a 
disc and the making of a contact by a child who is instructed to press 
down the key as soon as he sees the disc move : the median child's time. 

Rd = the time to see a lilue surface and react to it as for Rs. no 
reaction being permissible if the surface shown was red instead of blue. 







Muscle-Sense 






Age. 


Dwt.(B-\-G) 


MV(,B+G) 


Dwt.{B) 


Dwi.(G) 


6 


14.8 


5-2 


130 


16.8 


7 


13-6 


4 4 


132 


13.2 


8 


II. 4 


4.6 


12.2 


II .0 


9 


10. 


4.4 


10. 2 


10. 


10 


8.8 


4.4 


8.6 


9.2 


II 


8.6 


3.8 


10.2 


7.6 


12 


.7-2 


30 


7.6 


7.6 


i.i 


54 


30 


6.0 


5.6 


14 


5-6 


30 


5-2 


7.2 


15 


6.8 


2 .2 


6.2 


7.2 


16 


6.6 


2.4 


6.0 


6.8 


17 


5-8 


2.6 


6.0 


6.4 



The Influence of Maturity 



107 



Sensitiveness to Color-differences 



Age. 


Dcol.iB+G) 


MV(B-\-G) 


Dcol.{B) 


Dcol.{G) 


6 


9.6 


1.8 


8.3 


9.6 


7 


9 





2.1 


8.3 


9.6 


8 


8 


3 


2.3 


9.6 


7.0 


9 


6 


3 


2.2 


6.1 


6.6 


ID 


5 


4 


1-9 


6.0 


5-2 


II 


5 


4 


1-7 


6.0 


4-9 


12 


5 


I 


1-5 


4.8 


51 


13 


4 


6 


1-7 


5-2 


41 


14 


4 


7 


1-4 


4.8 


4.6 


15 


4 


4 


I.I 


4.1 


4.6 


16 


4 


3 


1-3 


4-3 


4.0 


17 


3 


•9 


1-4 


4.0 


4-9 



Force of Suggestion 



Age. 


H(B+G) 


MViB+G) 


H{B) 


H{( 


-) 


6 


42.0 


17.0 


43-5 


42.5 


7 


45 





155 


43-5 


43 


5 


8 


47 


5 


13-5 


450 


49 


5 


9 


50 





10.5 


50.0 


49 


5 


10 


43 


5 


12.5 


40.0 


44 





II 


40 





"■5 


38.5 


40 





12 


40 


5 


9.0 


38.0 


41 





13 


38 





9.0 


370 


38 





14 


34 


5 


9-5 


310 


33 


5 


J5 


35 





10.5 


330 


38 





16 


34 


5 


lO.O 


32.0 


38 


5 


17 


27 





12 .0 


25.0 


31 






Voluntary Motor Ability 



T{D-^G) MV{B+G) T{B) 



Age. 


T{D + G 


6 


20.8 


7 


22.5 


8 


24.4 


9 


254 


ID 


27.0 


II 


29.0 


12 


29.9 


13 


28.9 


14 


30.0 


15 


3i» 


16 


32.1 


17 


33-8 



MV{B) T{G) MV{G) 



2.4 


21 .0 


2.9 


22.8 


2.9 


24.9 


2.5 


25.8 


2.8 


27.7 


3-3 


29.7 


3-3 


30.3 


2.8 


29.8 


3.6 


31-2 


30 


313 


3-3 


330 


2.9 


350 



2-5 


19.7 


2.7 


21.2 


3-4 


239 


2.5 


25.0 


2.6 


26.9 


3-2 


27.8 


3-1 


29.6 


30 


28.1 


3-2 


28.0 


2.6 


29.8 


30 


31-8 


2.4 


315 



2.5 

2-5 
2 .2 
2.9 
2.8 

30 
30 

3-3 
3-4 
3-2 

3-4 
2.3 



io8 



Educational Psychology 



Fatigue 



Age. 


F(B+G) 


Ml/(B+G) 


F(i?) 


MV{B) 


F(G) 


MV{G) 


6 


21.4 


8.1 


22.8 


9-4 


21.3 


7.0 


7 


21 .O 


8 


9 


22 


5 


9 


7 


20.2 


6.7 


8 


24.0 


7 


3 


24 


7 


8 


3 


233 


71 


9 


21 .0 


7 


I 


22 


5 


6 


7 


20.7 


7.8 


lO 


22.0 


7 


5 


22 


7 


7 


8 


19.0 


71 


II 


20.0 


6 


2 


20 


3 


6 


5 


18.0 


5-5 


12 


16.0 


6 


3 


18 





6 





14.0 


6.7 


13 


14 5 


6 


4 


15 


8 


6 


7 


H-7 


5-8 


H 


14.0 


6 


5 


17 


8 


6 


2 


12 .0 


6.1 


15 


12.7 


5 


8 


13 


8 


4 


9 


II-5 


5-7 


i6 


147 


5 


2 


15 


3 


4 


6 


II. 7 


56 


17 


13.8 


5 


3 


14 


5 


6 


3 


13-5 


4-3 






Reaction Time 






Age. 


RsiB-\-G) 


MV{B-\-G) 


Rs{B) 


Ml/(5) 


Rs{G) 


MViG) 


6 


295 


50 


282 


46 


295 


54 


7 


292 


55 


267 


46 


315 


52 


8 


262 


39 


245 


39 


260 


31 


9 


250 


41 


243 


54 


255 


49 


lO 


215 


36 


2IO 


26 


225 


43 


11 


195 


34 


185 


31 


206 


34 


12 


187 


31 


178 


27 


198 


35 


13 


187 


30 


178 


29 


205 


35 


14 


180 


29 


180 


30 


187 


30 


15 


172 


27 


167 


23 


189 


27 


i6 


155 


23 


147 


16 


172 


26 


17 


155 


3: 


5 


147 


19 


163 


26 



Reaction with Discrimination and Choice 



Age. 


Rd{B-\-G) MV{B+G) 


Rd{B) 


MV{B) 


Rd{G) 


MV{G) 


6 


525 


60 


535 


53 


510 


65 


7 


530 


81 


490 


88 


528 


94 


8 


478 


65 


480 


57 


475 


55 


9 


450 


68 


445 


63 


460 


72 


ID 


410 


49 


400 


49 


415 


45 


II 


385 


58 


387 


58 


388 


57 


12 


370 


55 


385 


60 


370 


49 


13 


395 


58 


360 


51 


415 


55 


14 


365 


49 


367 


45 


355 


54 


15 


335 


49 


311 


55 


345 


38 


16 


325 


43 


315 


39 


350 


39 


17 


312 


40 


305 


35 


315 


44 



The Influence of Maturity 109 

Just what do these median abihties of Table 10 mean? Just 
what do the differences between those for six and seven, seven 
and eight, etc., tell us about the development of mental traits in 
life? Just what do we learn about human nature from these 
comparisons of the capacities of children of different ages ? 

It is clear that an alteration in any mental trait in any individual 
with age might be due to the mere maturing of some characteristic 
of original nature or might be the creation of some environmental 
force. The educational inferences would be exactly opposite in 
the two cases. In the former we should say : This change comes 
as a gift from nature which we may not be able to refuse without 
damaging general growth. It is given as the partial basis and 
starting point for education. We do not have to try to get it. 
In the latter case we should say: This change comes as the 
earnings of training. It is a product of education. With a 
different training it might be absent. We may lack or possess it 
as we choose. 

Moreover, in the case of many measurements of mental traits, 
for instance those quoted, the change due to an individual's age 
would be possibly due not only to the maturing of the trait or 
the influence of training upon it, but also to the influence of both 
maturity and training upon the ability to understand and the wish 
to follow instructions and the ambition to do well in tests. This 
complex of traits we may call general ability in tests. It is even 
conceivable that the last factor was the sole cause of all the 
changes quoted above. 

As a matter of fact all three of these factors are involved in 
most of the changes of mental traits with age. Even if the changes 
are due directly to outside forces, in the form of the experiences of 
life and training, maturity may still count as a force cooperating 
with these or furnishing the conditions in the individual which 
permit their action on him to produce the mental changes in 
question. On the other hand, mere inner growth, no matter how 
potent, requires usually some stimuli from without. A child 
grows mentally in some kind of a world of experience, forming 
some habits. Only in thought can the contribution of his inner 
impulsions be separated off from the contribution of the outside 
stimuli by which the inner impulsions are roused to action. Further- 
more, a mental test with children almost always measures some- 



no Educational Psychology 

what general powers of comprehension as well as the special power 
of sensation, memory or the like that is its ostensible object. 

Hence mere knowledge of age differences in a mental trait, 
without knowledge of how their causation is distributed amongst 
these three factors, does not allow us to estimate the amount of 
influence of maturity in determining an individual's status in 
respect to the trait. The total age change must at least be divided 
between mere maturity and the added training which has accom- 
panied maturity. Until this is done we cannot progress far 
beyond the vague commonplaces of common observation. 

The Difficulties in Inferring Changes in Individuals zvith Age 
from Differe,nces Between Old and Young Indidivuals 

So far upon the supposition that by changes in mental traits 
with age, we mean changes in the same individuals measured at 
different ages. The average change would then be the average 
of the changes in all the individuals studied. But in the studies 
that have been reported, the difference between the figures for, 
say, ten and eleven years, is not the average of the changes of 
all the individuals studied and need not in any real way describe 
them. 

For (i) the difference between the average of a group at ten 
and of the same group at eleven years does not describe the real 
individual changes; and (2) when we measure ten- and eleven- 
year-olds as we find them in school or elsewhere, we can not be 
sure that the eleven-year-olds represent what the ten-year-olds will 
become. 

The first point will be made clear by the following illustration. 
Suppose that eighteen boys showed at the age of ten and a 
half years the abilities in some mental trait denoted by the 
measures in the first column and made the gains during the next 
year shown by the figures in the second column, their consequent 
records at eleven and a half years being given in the third column. 
(Case I.) 

If instead of this complete record we had simply the figures : 
10I/2 years, Av. 5.94; nl/o years, Av. 8.16; Change in average 
ability, 2.22, we should lack the essential features of our fact ; 
viz., (i) the variability of the changes and (2) the antagonism 
between ability at ten and a half years and growth during the 



The Influence of Maturity in 

Case I Case 2 



Ability 




Ability 


Ability 




Ability 


at loK 


Change 


at 11^ 


at io>^ 


Change 


at iiyi 


2 


5 


7 


2 





2 


2 


5 


7 


2 





2 


3 


4 


7 


3 


I 


4 


4 


3 


7 


4 





4 


4 


4 


8 


4 


I 


5 


5 


4 


9 


5 


3 


8 


5 


I 


6 


5 


I 


6 


6 


3 


9 


6 


I 


7 


6 


3 


9 


6 


I 


7 


6 


I 


7 


6 


3 


9 


6 


I 


7 


6 


3 


9 


7 


I 


8 


7 


I 


8 


7 


3 


10 


7 


4 


II 


7 


I 


8 


7 


4 


II 


8 





8 


8 


3 


II 


9 


I 


10 


9 


4 


13 


9 





9 


9 


5 


14 


II 





II 


II 


5 


16 



Avg. 5.94 2.22 8.16 Avg. 5.94 2.22 8.16 

next year. There is an almost inevitable tendency, when a single 
figure is given to represent change, to fancy that all children show 
exactly or nearly that amount of change. This is of course never 
true. Rate of change as well as absolute ability is variable. And 
it is precisely in relating the different degrees of progress found 
in individuals to their original capacities and individual circum- 
stances, that educational insight will accrue. The real individual 
changes may often prove to be a partial function of the amount 
of ability already acquired, as in our illustration. The mere 
change in average ability given above could have come as well 
from a condition, shown in Case 2, just opposite in this respect 
to that of Case i. 

In Case 2, the better a boy is at ten and a half years the more he 
gains ; whereas in Case i, the better he was the less he gained. Case 
2 would, I venture to prophesy, be the fact in the progress with 
age of real mental efficiency, while with physical growth from 
thirteen to eighteen we should have something like Case i, the 
children who had matured early and so attained high stations in 
stature growing little, while those who matured slowly would keep 
on growing at a fair rate. In brief, the growth of averages does 



112 Educational Psychology 

not accurately describe, and may positively misrepresent, the real 
growth of the individuals in the group. 

Our second point was that the eleven-year-olds tested need not 
represent what the ten-year-olds would become. The average 
changes stated in the quotations at the beginning of this chapter 
were obtained from facts like the following: Ten-year-olds 
A, B, C, D, E, F, G, H, etc., give an average x ; eleven- 
year-olds, L, M, N, O, P, etc., give an average y. The 
change in average ability is 3/ - x. The individuals of the two 
groups not being identical, the chance is given for the fallacy of 
selection to run riot. The eleven-twelve-year-olds certainly 
represent only those ten-eleven-year-olds who will live ; in any test 
given in schools they represent only the ten-eleven-year-olds v/ho 
will continue in that type of school. Now if one measures a mental 
trait in elementary school children he gets for different ages some- 
thing like the following figures: — 12 year-olds, 100; 13-year-olds, 
90; 14-year-olds, 70; 15-year-olds, 30. 

Nobody can imagine that the fifteen-year-olds here would give 
anything like a fair sampling of what the twelve-year-olds would 
become. The brightest twelve-year-olds pass out of the grammar 
school before they are fifteen. Some mental defectives leave for 
special institutions. Some moral defectives leave for reform 
schools or the free life of thievery and trampdom. Some chil- 
dren of very poor parents go to work. If we fill up our quota 
of fifteen-year-olds by adding 70 from high school pupils we 
jump from the frying pan into the fire, for these are a selection 
of the brighter, the more ambitious, those whose parents are 
fairly well off financially and are intellectually inclined. 

I conclude, therefore, that the development of mental traits with 
age has not been and can not be adequately measured by such 
studies as those quoted. To measure it we must repeat measure- 
ments upon the same individuals and for all purposes of infer- 
ence preserve intact each of the individual changes. In connec- 
tion with each of them account must be taken of the training 
which the individual in question has undergone. 

What measurements we do have may serve, however, to cor- 
rect two errors of common opinion. The notion that the increases 
in ability due to a given amount of progress toward maturity 
are closely alike for all children save the so-called " abnormally 
precocious " or "retarded " is false. The same fraction of the 



The Influence of Maturity 113 

total inner development, from zero to adult ability, will produce 
very unequal results in different children. Inner growth acts 
differentially according to the original nature that is growing. 

The notion that maturity is the main factor in the differences 
found amongst school children, so that grading and methods of 
teaching should be fitted closely to 'stage of growth,' is also false. 
It is by no means very hard to find seven-year-olds who can do 
intellectual work at which one in twenty seventeen-year-olds would 
fail. Although the influence of inner growth in causing individual 
differences cannot be measured from the data at hand, an upper 
limit for it can be set. Take discrimination of weight as a sample 
case. Since early age differences are in part due to training and 
since training acts here in the same direction as does maturity, 
the average inner growth from, say, ten to seventeen must produce 
less than the average difference found between ten-year-olds and 
seventeen-year-olds. Since, in Gilbert's study, the seventeen-year- 
olds and ten-year-olds both come from school pupils, including 
pupils in the high school, the seventeen-year-olds represent at 
least as high ranking pupils in mental respects as the ten-year-olds 
would become. So the effect of average inner growth from ten 
to seventeen is at the outside a reduction in the least noticeable 
difference from 8.8 to 5.8 grams. But many ten-year-olds noticed 
a difference of 5.8 grams or less. Gilbert's 4.4 (for the average 
deviation of the individual ten-year-olds from their C. T.) would 
put 30 per cent of them above the average seventeen-year-old 
unless the distribution of individual differences among the ten- 
year-olds is markedly eccentric. And within the ten-year-olds 
there is a range of variation at least five times as great as that 
between the average ten-year-old and the average seventeen-year- 
old. The range cannot be less than four times 4.4 g. unless the 
distribution (surface of frequency) is of a form never found in 
measurements of discrimination of weight. Hence even the top- 
most limit for the average effect of these seven years' maturity is 
surely less than one sixth of the effect of the extreme differences 
in ancestry and training upon children of the same age. 



CHAPTER VII 

The Influence of the Environment 

Difficulties in Estimating the Amount of Influence of the 

Environment 

The questions suggested by the title of this chapter inchide 
the effects on individuals of every environmental force, including 
all the agencies for intellectual and moral education. Precise 
quantitative answers can be given to hardly any of them. 

Theoretically, there is no impossibility. Once we have esti- 
mated the original nature of a man or group of men, we have 
simply to note the mental changes consequent upon this or that 
change in climate, food, school training, friendship, sermon, occu- 
pation, etc. Practically, the complexity of the action of physical 
and human influences upon intellect and character hampers scien- 
tific study and favors guesswork. The environment includes a 
practical infinitude of different causes ; these act differently upon 
different types of original nature and at different ages and with 
different cooperating circumstances ; in many cases their action 
is very complex and must be observed over long intervals of 
time. Indeed it has been common to deny even the possibility 
of a science of the dynamics of human nature and to remain 
content with the haphazard opinions of novelists, proverb makers 
and village wise men. 

Moreover, it is only by the utmost ingenuity and watchfulness 
that studies of changes in human nature can be freed from a char- 
acteristic fallacy — that of attributing to training facts which are 
really due to original nature or to selection. For instance, col- 
lege graduates are found to have a much greater likelihood of 
being elected to Congress than other men have. Therefore it 
is said that a college education causes to some extent political suc- 
cess. But it is clear that even before they went to college the 
group of youth who dW go were different from those who did not. 

(114) 



The Influence of the Environment 115 

Their later election to Congress may as well have been due to 
the mental traits which they possessed by birth or otherwise and 
which caused their inclusion in the class ' boys who go to college ' 
as to any changes produced in them by the college training itself. 
In other words, that they were the class selected by the college 
is as important a fact as that they were the class trained by it. 

Again it is said : " Who can doubt the enormous disciplinary 
value of the study of Latin and Greek when we see the admirable 
intellects of the men so trained in the English universities?" 
But being born from the class whose children go to the university 
of itself ensures to an individual uncommon mental ability. 

To avoid this confusion of causes which train with those which 
select is extremely hard. Any class of individuals studied because 
they have been subjected to a certain training is almost sure to 
be a class not only trained by but also selected by that training. 
Suppose that one wishes to study the influence of a high-school 
course, or that of the classical as opposed to the scientific course, 
or that of training in independent research, or that of immoral 
surroundings. High school graduates are but one fifth of gram- 
mar school graduates ; and no one would claim that they repre- 
sent an entirely random picking therefrom. They are surely 
selected for better birth, better abilities and better ideals. Again, 
in most high schools the graduate of the classical course represents 
not only a different training, but also a different selection, com- 
monly a superior selection.* So also scientific men are a class 
resulting not only from the training given by research work, but 
also from the selection of those eager to do and fitted to do that 
work. Children brought up in a morally bad environment are 
almost sure to be of morally inferior ancestry. The ordinary 
arrangement of social and educational careers rarely presents 
.us with convenient cases of similar natures, some with, some with- 
out, the form of training under consideration. 

The difficulty of eliminating the influence of selection is no 
excuse for its neglect. Yet one may hunt through thousands of 
pages of discussions of the influence of certain studies, school 
systems, schemes of culture, religious beliefs, etc., without finding 
a hint of its recognition. 

Either because of the general complexity of environmental in- 
fluences upon any mental trait and the mixture of selective 

*This apparently is becoming less common every year. 



ii6 Educational Psychology 

with formative influences or because of the infrequency of scien- 
tific habits and ideals in students of sociology and education, 
there are few facts of sufficient security and precision to be 
quoted. Only rarely has educational science progressed beyond 
the reasoned opinions of more or less capable judges. We have 
our beliefs about the causal relations between a hot climate and 
indolence, necessity and invention, lack of parental control and 
crime, religious training and morality, etc., but we can not be 
said to know these influences with adequate surety or to have 
any knowledge whatever of their precise amount. 

A refusal to believe insecure opinions about the influence of 
differences in training in producing differences in human indi- 
viduals does not at all imply disbelief in their influence. Such 
would be absurd. When the original natures are the same, every 
difference that the individuals later show must be due to differ- 
ences in the outside forces operating upon them. And any differ- 
ence in outside forces always has its effect. No man is left un- 
changed by even the very least of the environmental forces that 
act upon him. Men are the creatures of circumstance. But they 
are creations whose final patterns are determined in part by sex, 
race, ancestry and conditions of origin. Circumstances alter 
natures, but the alterations vary with the nature altered. It is 
precisely because common opinions have thought verbally in terms 
of 'man-training-product of training', instead of concretely in 
terms of 'men-training-products, — each of an individual's nature 
in interaction zvith his training ' , that a sound science of the in- 
fluence of the environment has hardly been begun. 

One of the best services such a science can render is to guard 
its students against such verbal plausibilities. For example, 
knowledge is not proportional to opportunity in the sense that an 
individual's degree of knowledge can be foretold from his degree 
of opportunity. Wealth does not create wealth in the sense that 
what a man will have can be estimated from what he now has. 
A good home does not make good children in the sense of doing 
so always and in proportion to its goodness. Being treated like 
slaves may not debase all and never debases all alike. The product 
of the environment is always a result of two variables, it and the 
man's nature. 

Two of the corollaries of this axiom are of special significance. 
The first is that the environmental stimulus adequate to arouse a. 



The Influence of the Environment 117 

certain power or ideal or habit in one man may be hopelessly 
inadequate to do so in another. Washing bottles in a ding-shop 
was, if a common story is true, adequate to decide Faraday's 
career, and the voyage on the Beagle is reputed to have made 
Darwin a naturalist for life. But if all the youth of the land were 
put to work in drug-shops and later sent on scientific expeditions, 
the result would not be a million Faradays and Darwins, or even 
a million chemists and naturalists. All that one man may need 
to be free is a vote ; but even a long education in self-direction 
may be inadequate for another. Being told a few words suffices 
to secure the habit of reading in one child, while the child beside 
him remains illiterate after two years of careful tuition. The 
amount of stimulus required in some cases is so infinitesimal 
that the power seems to spring absolutely from the man himself. 
In other men no agency is found potent enough to arouse a trace 
of the desired result. 

The second corollary is that each man in part selects his own 
environment. The boy turns his eyes from the book. Even if 
his eyes attend to it, his mind does not. Even if for the time he 
lets it move him, it may be disregarded in memory. That connec- 
tion which brings satisfaction to one man and is thereby given 
power over him, may disgust another nature and so be repudiated 
by it. As this world's nature selects for survival those animals 
which are adapted to live in it, so any individual selects, by action, 
attention, memory and satisfaction, the features of the environ- 
ment which are to survive as determinants of his intellect and 
character. 

Common opinion and the older literature of sociology and edu- 
cation neglected the differential action of the environment in 
accord with the nature it acted on, but it would be possible for 
a student, enamored of the simplicity of the explanation of all 
men's differences by differences in their original make-up, to 
neglect equally obvious facts of another sort. He might be 
tempted to claim that, since the features of civilization, — the 
acts, words, books, customs, and institutions of men, — have been 
invented and perpetuated by human natures, and since conse- 
quently the environment in all important respects is itself due to 
original nature, — therefore original nature is at bottom the cause 
of almost all of human destinies. " A people gets as good govern- 
ment as it deserves ; a race has the environment its own nature 



ii8 Educational Psychology 

has found and chosen: a man in essential matters is treated as 
his nature decides." So he might carelessly claim. 

Many important features of the environment are thus due to 
the original nature of the human race as a whole, but no one 
man's nature and, under modern conditions, no one nation's or 
race's is similarly responsible for the particular environment that 
it meets. Forces set in motion by others play upon it. At the 
best it can select only negatively by disregard, and at the worst 
it may be molded directly against nature. 

Even when it is known, and with some precision, that a given 
difiference is due to some difference in training, there may be 
doubt or total ignorance as to what difference in training caused 
it. And even when it is known that a given difference in train- 
ing has been operative and has produced an effect, there may be 
doubt or ignorance about what the effect is. 

Illustrations of the former case are abundant in history. His- 
tory is in fact largely a record of unexplained changes in human 
nature. Nearly all the intellectual and moral differences between 
the modern English, French, or Germans and their barbarous 
ancestors of two thousand years ago are due to differences 
in environment. The original natures of the stocks may have 
altered somewhat during that time, but surely not much. Our 
thoughts and ways of thinking and our habits, customs and ideals 
have been and are being made very unlike those of our ancestors 
by some outside forces. But what the forces were and how each 
contributed to the result is not known. 

Illustrations of the latter case form a large proportion of the 
facts studied under the vague rubric of education. Such and 
such children have gone to school, they have been taught by such 
and such teachers, using this and that method, at a cost of so 
many dollars, with aid of a material plant worth so much ; but 
what has come of it all, no cautious thinker would dare say. 
What has been and is being done to children in schools is more 
or less well described in official and private records, but what hap- 
pens in children as its consequence is largely unknown. 

So much for the attitude in which a student of human nature 
must approach the problems of the effect of different environ- 
ments on identical natures, of the effect of the same environment 
on different natures, and of the effect of the endless different co- 
operations of environments and natures. 



The Influence of the Environment 



119 



Samples of Measurements of the Influence of the Environment 

I shall report four samples of studies of the influence of the 
environment upon intellect and character. The first is Galton's 
History of Twins ['83], a study of the amount of its influence in 
comparison with that of original nature. The second, from Cat- 
tell's Statistical Study of American Men of Science ['06], is a 
study of the effect of early opportunity upon scientific achieve- 
ment. The third is Rice's study of the effect of different school 
environments upon ability in spelling and arithmetic ['97 and 
'02]. The fourth is a study of the effect of changing environment 
upon the choice of a profession by scholarly youth. 

Galton collected reports from parents concerning twins who 
were closely similar in infancy but whose environments differed, 
and twins who were in infancy notably unlike, but whose environ- 
ments were in all important features identical. The increase of 
differences in the former case and of resemblances in the latter 
gives a measure of the influence of the environment. The per- 
sistence of similarities in the former case and of differences in the 
latter gives a measure of the influence of original nature. 

This evidence in the first case consists of illustrations of iden- 
tical mental habits, tastes, associations of ideas and suscepti- 
bilities to mental diseases. The cases of unlikeness seem to him 
to be due to such alterations in the amount of energy as could be 
caused by illness or lowered nutrition rather than to fundamental 
qualities of mind. 

The evidence in the case of the twenty pairs in the second 
group shows no exceptions to the rule that no weakening of 
inborn differences by similarities of nurture is observable. The 
following are representative parental observations : — 

1. One parent says: — "They have had exactly the same nur- 
ture from their birth up to the present time; they are both per- 
fectly healthy and strong, yet they are otherwise as dissimilar as 
two boys could be, physically, mentally, and in their emotional 
nature." 

2. " I can answer most decidedly that the twins have been 
perfectly dissimilar in character, habits, and likeness from the 
moment of their birth to the present time, though they were 
nursed by the same woman, went to school together, and were 
never separated till the age of fifteen." 



120 Educational Psychology 

3. " They have never been separated, never the least differently 
treated in food, clothing, or education; both teethed at the same 
time, both had measles, whooping-cough, and scarlatina at the 
same time, and neither had any other serious illness. Both are 
and have been exceedingly healthy and have good abilities, yet 
they differ as much from each other in mental cast as any of my 
family differ from another." 

4. " Very dissimilar in body and mind ; the one is quite retir- 
ing and slow but sure; good-tempered, but disposed to be sulky 
when provoked ; — the other is quick, vivacious, forward, acquiring 
easily and forgetting soon; quick-tempered and choleric, but 
quickly forgetting and forgiving. They have been educated to- 
gether and never separated." 

5. " They were never alike either in body or mind and their 
dissimilarity increases daily. The external influences have been 
identical ; they have never been separated." 

6. " The two sisters are very different in ability and dispo- 
sition. The one is retiring but firm and determined ; she has no 
taste for music or drawing. The other is of an active, excitable 
temperament ; she displays an unusual amount of quickness and 
talent, and is passionately fond of music and drawing. From 
infancy, they have been rarely separated even at school, and as 
children visiting their friends, they always went together." 

7. " They have been treated exactly alike ; both were brought 
up by hand ; they have been under the same nurse and governess 
from their birth, and they are very fond of each other. Their 
increasing dissimilarity must be ascribed to a natural difference 
of mind and character, as there has been nothing in their treat- 
ment to account for it." 

8. '' They are as different as possible. [A minute and unspar- 
ing analysis of the characters of the two twins is given by their 
father, most instructive to read, but impossible to publish without 
the certainty of wounding the feelings of one of the twins, if 
these pages should chance to fall under his eyes.] They were 
brought up entirely by hand, that is, on cow's milk, and treated 
by one nurse in precisely the same manner." 

9. " The home-training and influence were precisely the same, 
and therefore I consider the dissimilarity to be accounted for 
almost entirely by innate disposition and by causes over which we 
have no control." 



The Influence of the Environment 121 

10. " This case is, I should think, somewhat remarkable for 
dissimilarity in physique as well as for strong contrast in char- 
acter. They have been unlike in body and mind throughout their 
lives. Both were reared in a country house, and both were at 
the same schools till act. 16." 

The two lines of evidence taken together justify, in Gal ton's 
opinion, the following general statements : 

" We may, therefore, broadly conclude that the only circum- 
stance, within the range of those by which persons of similar 
conditions of life are affected, that is capable of producing a 
marked effect on the character of adults, is illness or some acci- 
dent that causes physical infirmity. . . . The impression that 
all this leaves on the mind is one of some wonder whether nurture 
can do anything at all, beyond giving instruction and professional 
training. There is no escape from the conclusion that nature 
prevails enormously over nurture when the differences of nurture 
do not exceed what is commonly to be found among persons of 
the same rank of society and in the same country." 

Even in the hands of a master, the collection of data through 
correspondence is inferior to direct observation and measure- 
ment. Galton was misled to believe that twins fall naturally into 
two groups, those much alike, and those little alike, in infancy. 
They do not. His correspondents may have made careless re- 
ports in other respects also. However, it will be remembered that 
with respect to fifty pairs of twins, objectively measured, the 
facts showed that the existing differences in home training had 
very slight effects upon the six mental abilities tested. 

The conditions of nurture of men of great achievement have 
been studied by De Candolle ['73], Galton ['74], Jacoby ['81], 
Odin ['95], Ellis ['04], Cattell ['06], and others. Within any 
one nation such men are more likely than chance would allow to 
be brought up in thickly settled districts, in particular in cities, 
still more particularly, in the case of men of science or letters, 
in cities containing universities ; by parents in comfortable or 
more than comfortable financial circumstances ; and to have re- 
ceived a good education. 

Such facts are used in Odin, and by Lester F. Ward ['06] 
following him, as evidence that the number of men of great achieve- 
ment could be increased many times over if all men had in vouth 
the stimulus of an intellectually active city, freedom from pro- 



122 



Educational Psychology 



ductive labor, and good school training. But obviously the fea- 
tures of the successful man's surroundings, enumerated above, 
might all be the secondary results of superior parentage. If men 
of high capacity go to live in cities, their sons will be born and 
reared in cities ; if men of scientific and literary gifts are attracted 
to university cities, such cities will, on grounds of heredity alone, 
produce future scientific and literary men. If men of high achieve- 
ment are born of men of over-average achievement, they will not 
be brought up by day-laborers and without education as often 
as chance would dictate. The parent's achievement leads for- 
ward to these environmental conditions as truly as the son's 
achievement leads back to them. So nothing is proved by them. 
From Table ii [Cattell, '06], one can, according to his point of 



TABLE II. 

Distribution of 867 Men of Science Born in the United States. 

Birthplace. Per 

Million 

I.-V* VI.-X.* Total. i860. 

North Atlantic Division. 

Maine 19 10 29 46. i 

New Hampshire 7 8 15 46.0 

Vermont 9 9 18 57-1 

Massachusetts 60 74 134 108 . 8 

Rhode Island 4 i 5 28.6 

Connecticut 26 14 40 86.9 

New York 99 84 183 47 . 2 

New Jersey 9 19 28 41.6 

Pennsylvania 32 34 66 23.7 

South Atlantic Division. 

Delaware o 2 2 17.8 

Maryland 12 14 26 37-8 

District of Columbia i 2 3 39-9 

Virginia 5 8 13 

West Virginia i o i 8.8 

North Carolina i 4 5 5.0 

South Carolina 2 3 5 7.1 

Georgia i 2 3 2.8 

South Central Division. 

Kentucky 6 2 8 6.9 

Tennessee 5 i 6 5.4 

Alabama i i 2 2.1 

* Column I -V. gives the facts for men of the highest ability; column 
VI. -X. gives the facts for the 500 men of less ability. 



The Influence of the Environment 



123 



I. -v.* 

Mississippi 1 

Louisiana i 

Texas o 

North Central Division. 

Ohio 42 

Indiana 17 

Illinois 24 

Michigan 12 

Wisconsin 11 

Minnesota i 

Iowa 6 

Missouri 4 

North Dakota 

South Dakota 

Nebraska i 

Kansas 5 

Western Division. 

Montana 

Wyoming 

Colorado o 

New Mexico 

Arizona 

Washington i 

California 5 

Alaska 

Hawaii i 

Philippine Islands 

Total 432 



Birthplace. 




Per 

Million 


VI.-X.* 


Total. 


i860. 





I 


1-3 





I 


1-4 


3 


3 


4.9 


33 


75 


32.1 


II 


28 


20.7 


18 


42 


24-5 


15 


27 


36.0 


24 


35 


45-1 


3 


4 


23.2 


14 


20 


29.6 


10 


14 


II. 8 


I 


2 


69 -3 


2 


7 


65-3 



o 
6 



I 
II 



87.2 



86.2 
28.9 



435 



867 



27.6 



view, get evidence that edticational opportunity counts enormously 
or that it counts sHghtly in the relative production of scientific 
men by the different states of this country. 

For instance, the most striking fact is the high position of New 
England and the low position of the southern states. The advo- 
cate of great influence from opportunity may plausibly say that 
from 1870 to 1885, the time when most of the men in question 
were from 10 to 30 years of age, life in New England meant 
cities, schools, books, lectures, the personal example of scholarly 
men and freedom from poverty, whereas life in the south meant 
the reverse. But the advocate of little influence may retort that 
Maine, New Hampshire and Vermont should not, on these 
grounds, have been so superior to Rhode Island ; or Louisiana so 



124 Educational Psychology 

inferior to Texas ; or Missouri so inferior to Wisconsin. He may 
insist that the chief gift of Massachusetts parents to their sons was 
the original nature which in earher days developed commerce 
and manufactures, established the schools and libraries, and raised 
life above a daily struggle for physical necessities, while the 
southern planters and their servants were content to leave nature 
unimproved. 

Such a conflict of opinion is found between Professor Cattell, 
who gathered the data of Table ii, and Professor Woods. Some 
of the comments of the former are : — " The inequality in the 
production of scientific men in different parts of the country 
seems to be a forcible argument against the view of Dr. Galton 
and Professor Pearson that scientific performance is almost ex- 
clusively due to heredity. It is unlikely that there are such 
differences in family stocks as would lead one part of the country 
to produce a hundred times as many scientific men as other parts. 
The negroes may have a racial disqualification, but even this 
is not proved. The main factors in producing scientific and 
other forms of intellectual performance seem to be density 
of population, wealth, opportunity, institutions and social 
traditions and ideals. All these may be ultimately due to race, 
but, given the existing race, the scientific productivity of the 
nation can be increased in quantity, though not in quality, almost 
to the extent that we wish to increase it 

" My general impression is that certain aptitudes, as for mathe- 
matics and music, are mainly innate, and that kinds of character 
and degrees of ability are mainly innate, but that the direction of 
performance is mainly due to circumstances, and that the environ- 
ment imposes a veto on any performance not congenial to it." 
['06, pp. 734-735] 

The cities in which five or more of the thousand men of science 
were born, are given in Table 12. [Cattell, '06, p. 738] The 
author of the study is cautious in estimating the beneficial results 
of city life. He says simply, " Of the 866 men native to the 
United States, 224 were born in the cities which in 1900 had a 
population of more than 25,000. These places had in i860 a popu- 
lation of about 4,500,000 as compared with a rural population of 
about 27,000,000. The urban population was about one sixth of 
the rural population and produced more than a quarter of the 
scientific men. The urban birth rate was 50 and the rural birth 



The, Influence of the Environment 125 

rate was 23.8. The superior position of the towns is doubtless 
due to a more favorable environment, but it may also be in part 
due to the fact that the parents of these scientific men were the 
abler clergymen and others of their generation who were drawn 
to the cities. ['06, pp. 738-739] 

TABLE 12. 

Distribution in Different Places. 

According to Birthplace Per 

Million 
I-V VI.-X. Total. i860. 

New York, N. Y 33 25 58 71.2 

Boston, Mass 24 19 43 241 . 8 

Philadelphia, Pa 12 16 28 49 • 5 

Baltimore, Md 9 11 20 94 -i 

Cincinnati, 6 6 12 74-5 

Brooklyn, N. Y 3 8 ii 39-4 

Chicago, Ills 5 3 8 73.2 

Buffalo, N. Y 3 4 7 86.2 

St. Louis, Mo 2 5 7 43.5 

Cambridge, Mass 4 2 6 230 . 2 

Cleveland, 4 2 6 140 . 5 

Salem, Mass i 5 6 269 . 6 

Milwaukee, Wis i 4 5 no. 5 

Newark, N.J 3 2 5 69 . 5 

San Francisco, Cal 2 3 5 88 .0 

Total 112 115 227 

With respect to the circumstances of education " it appears 
that those who attend the larger universities are not of higher 
average performance than others 

"There is no significant difference in rank between the 515 men 
who attended the larger institutions and those who attended 
smaller colleges or none. It might be supposed that abler stu- 
dents would be attracted to a university such as Harvard, and 
that they would have greater opportunities there, but this appears 
not to be the case. So far as it goes, this favors the theory that 
men of science are born such and are not dependent on the en- 
vironment for the quality of their performance 

" The conditions are similar in the case of the doctor's desfree."' 
['06, pp. 740-741] 



'&' 



Dr. Rice's study is quoted at some length because it was the 
first of a series of studies of the actual results of school work. 



126 



Educational Psychology 



still few in number, but destined to increase rapidly with increasing 
scientific interest in school administration. 

Dr. Rice ['97] tested the spelling ability of some 33,000 children 
in twenty-one schools representing a great variety in spirit, 
methods, time given to spelling and in other respects. He then 
compared the conditions in schools where the pupils did well in 
spelling with those in schools where they did badly. He notes 
first of all the slight dififerences between schools, only 6 out of 
the 21 schools being outside the limits 73.3 and 77.9, and the 
decrease in variation amongst schools as we pass from lower to 
higher grades (see Table 13), facts which show that the dififer- 
ences in spirit or method that characterize schools can not make 
much difference in achievement. Of school systems where 
mechanical methods are in use as compared with more progressive 
systems he says : 

" Indeed, in both the mechanical and the progressive schools 
the results were variable ; so that while, in some instances, the 
higher figures were secured by the former, in others they were 
obtained by the latter ; and the same is true of the lower figures. 
For example. School B, No. 11, in which the best average (79.4) 
was obtained, belongs to a very progressive system ; while School 
A, No. 12, which made only 73.9, belongs to one of our most 
mechanical systems. And it is a peculiar incident that, in both 
these cities, the results in the only other school examined are 
exactly reversed, although the environment is about the same." 

He eliminates the possibility that home reading or cultured 
parents or English rather than foreign parentage is the cause of 
the differences amongst schools by making the comparisons of 
Table 14. 

TABLE 14. (No. 3 of the original account) 



Grade. 



d 


0) 

3i 

(A 

s 


*.-■ 


d 


PM 


6 


■2§ 


Children of 

Foreign 
Parentage. 


6 
1 


No. of Children 

Hearing Foreign 

Language at 

Home. 


6 

2 

> 

< 


Children of 
Unskilled 
Laborers. 


M 

2 

Si 

< 


Sbntbncb 
Test. 


■ Fourth . . 
Fifth.... 
Sixth... . 
Seventh. . 
Eighth. . . 


4 
4 
4 
4 
4 


27 
29 
22 
18 
19 


821 
829 
778 
566 
528 


64.7 

76. 

69.7 

78.8 

83.1 


155 

153 

185 

81 

72 


65.2 

77-4 
69.6 

82.5 
83.2 


159 

157 

165 

52 

64 


64.9 
76.7 
70.3 
81.5 
83.2 


129 
129 
119 

55 
76 


62.5 

74 5 
704 
76.8 
85. 



The Influence of the Environment 



127 



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1 vo \0 O O •<+ fO t^vO 00 1 ONONON'i-ONMO'^l lONO 
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The^ Influence of the Environment 



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130 Educational Psychology 

Dr. Rice further tabulated the results in accordance with the 
methods of instruction used in the different schools, interviewing 
some two hundred teachers for that purpose. He does not give 
the detailed results, but assures us that there is no reason to be- 
lieve that there is any clear choice between oral and written spell- 
ing, writing isolated words and writing sentences, the sight or 
flash method and its absence. Phonic reading does not make bad 
spellers, nor do written language work and wide general reading 
make good spellers. " In brief," says he, " there is no direct 
relation between method and results. . . . The results varied 
as much under the same as they did under different methods of 
instruction." 

That the amount of time given is not the cause of success in 
teaching spelling is shown by the facts of Table 13. Schools 
giving 15 or 20 minutes daily to spelling do as well as those 
giving 40 or 50. 

After this admirable array of " facts Dr. Rice jumps rather 
hastily to this speculative conclusion : " The facts here presented, 
in my opinion, will admit of only one conclusion, viz., that the 
results are not determined by the methods employed, but by the 
ability of those who use them. In other words, the first place 
must be given to the personal equation of the teacher, while 
methods and devices play a subordinate part." 

This statement should have been based upon a demonstration 
of a high coefficient of correlation between the measure of a class 
in spelling and the measure of its teacher in ability, or of a great 
increase in variability in spelling ability as we pass from the 
children taught by one teacher to the children taught by 10 or 
20 different teachers. I calculate that if the reliabilities of Dr. 
Rice's eighth grade averages are what they would seem to be from 
tests made in eighth grades by myself and my students,* the dif- 
ferences amongst them are not much greater than we would ex- 
pect by the law of chance if the teaching were in all cases equally 
efficient. The average deviation from their mean of the 12 eighth 
grade classes which were tested in the first half of the year is 1.9 ; 
that of the 13 tested in the last half of the year is 2.6; the 
average deviation by pure chance of 12 eighth grade classes of 
40 students each would be 1.9, the variability of individuals 

*These give a variability of 12.2 amongst the individuals of the grade. 



The Influence of the Environment 131 

being 12.2. So, in the case of the eighth grades, we may need no 
cause at all for the differences amongst schools save the inaccur- 
acy of the averages due to the small number of cases. 

Dr. Rice measured the arithmetical ability of some 6,000 children 
in 18 different schools in 7 different cities ['02]. The results 
of these measurements are summarized in Table 15. This table 
" gives two averages for each grade as well as for each school as 
a whole. Thus, the school at the top shows averages of 80.3 and 
83.5, and the one at the bottom, 25.2 and 31.8. The first repre- 
sents the percentage of answers which were absolutely correct ; the 
second shows what per cent, of the problems were correct in prin- 
ciple, i. e., the average that would have been received if no me- 
chanical errors had been made. The difference represents the 
percentage of mechanical errors, which, I believe, in most in- 
stances, makes a surprisingly small appearance." 

From these results Dr. Rice seeks the causes of excellence in 
arithmetical work, as in the case of spelling, by comparing the 
conditions in the successful schools with those in the unsuccessful. 
He deals seriatim with ( i ) the home environment of the pupils ; 
(2) the size of the classes; (3) the age of the children; (4) the 
time of day of the test; (5) the time devoted to arithmetic in 
the school; (6) the amount of home work required; (7) the 
methods of teaching; (8) teaching ability as represented by a 
combination of education, training and the personality of the 
teacher; (9) the course of study; (10) the superintendent's 
training of teachers ; ( 1 1 ) the establishment of demands in regard 
to results; (12) the testing for results (a) by teachers alone, 
(b) by teachers and superintendents, (c) by principals, (d) by 
principals and superintendents. 

He finds that the work depends upon the method of testing 
for results, that teachers and pupils do about what is demanded of 
them, and that the best work appears when the superintendent, in 
connection with principals of schools, tests and rates the work of 
the classes. 

The following are samples of the reasoning by which he 
eliminates one after another of the possible causes : 

Home Environment 

" If the part that is played by the home environment should 
be as important as it is generally supposed to be, we should, of 



132 Educational Psychology 

course, expect to find that the schools represented in the upper 
part of the table had been attended by children from cultured 
homes, while those in the lower part had been attended by those 
whose home environment was very poor. However, if a line 
should be drawn across the middle of the table, and the schools 
above it compared with those below, such a condition would not 
be found. Indeed, careful inspection would show that the odds 
were certainly not in favor of the ' aristocratic ' districts. Of the 
eighteen schools, three in particular are representative of the 
latter, and the best of these secured the tenth place, while the 
others ranked eleventh and sixteenth, respectively. The school 
that ranked seventh was distinctively a school of the slums. That 
is to say, the school laboring under the poorest conditions in 
respect to home environment obtained a better standing than any 
one of the so-called aristocratic schools. The building which 
stands fifth is representative of conditions just a shade better 
than those of the slums. And when I add that, from the stand- 
point of environment, the schools of City I. did not average a 
single degree better than those of Cities VI. and VII., I have 
said enough to show that the poor results secured in the latter 
cities can not be condoned on the ground of unfavorable environ- 
ment. Thus, as in spelling, so in arithmetic, this mountain, upon 
close inspection, dwindles down to the size of a molehill." 

Si:::e of Classes 

" Equally surprising, if indeed not more incredible, may appear 
the statement that no allowance whatever is to be made for the 
size of the class in judging the results of my test. I shall not 
enter into the details in regard to this point, but will dismiss it 
with the remark that the number of pupils per class was larger 
in the highest six schools than it was in the schools of City VI., 
and that the classes were exceptionally small in the school that 
stands at the lower end." 

Age of Pupils 

His argument is here too lengthy to quote and is rather awk- 
ward, but sufficiently proves that the differences between schools 
could have been due only in a very slight degree, if at all, to differ- 
ences in the ages of the pupils. The obvious way to eliminate age 
is to .compare a group from City VI. or VII. with a group iden- 
tical in age and grade from City I. or III. 



The Influence of the Enviromnent 133 

Time of Day 

This can not be the cause of much of the difference found, for 
within any one city the time of day of the test makes Httle 
difference. 

The Time Devoted to Arithmetic in the School 

" A glance at the figures will tell us at once that there is no 
direct relation between time and result ; that special pressure 
does not necessarily lead to success, and, conversely, that lack of 
pressure does not necessarily mean failure. 

"In the first place, it is interesting to note that the amoimt of 
time devoted to arithmetic in the school that obtained the lowest 
average — 25 per cent. — was practically the same as it was in the 
one where the highest average — 80 per cent. — was obtained. In 
the former the regular time for arithmetic in all the grades was 
forty-five minutes a day, but some additional time was given. 
In the latter the time varied in the different classes, but averaged 
fifty-three minutes daily. This shows an extreme variation in 
results under the same appropriation of time. 

"Looking again toward the bottom of the list, we find three 
schools with an average of 36 per cent. In one of these, insuffi- 
cient pressure might be suggested as a reason for the unsatisfac- 
tory results, only thirty minutes daily having been devoted to 
arithmetic. The second school, however, gave forty-eight, while 
the third gave seventy-five. This certainly seems to indicate that 
a radical defect in the quality of instruction can not be offset by 
an increase in quantity. 

"If we now turn our attention from the three schools just men- 
tioned and direct it to three near the top — Schools 2, 3, and 4, 
City I. — we find the conditions reversed ; for while the two schools 
that gave forty-five minutes made averages of 64 per cent, and 
67 per cent., respectively, the school that gave only twenty-five 
minutes succeeded in obtaining an average of 69 per cent. This 
would appear to indicate that while, on the one hand, nothing is 
gained by an increase of time where the instruction in arithmetic 
is faulty, on the other hand, nothing is lost by a decrease of time, to 
a certain point, where the schools are on the right path in teaching 
the subject. Perhaps the most interesting feature of the table is 
the fact that the school giving twenty-five minutes a day came 
out within two of the top, while the school giving seventy-five 
minutes daily came out practically within one of the bottom." 



134 Educational Psychology 

The Amount of Home Work Required 

The greatest amount of home work was required in the lowest 
ranking city while it had been practically abandoned in the first 
five schools of the table. 

In the other cases the facts are given more vaguely, and in his 
presentation of positive evidence that differences in supervision 
by tests are the leading causes of the differences in achievement 
of the different schools, Dr. Rice seems to reach his conclusion 
simply from observing (i) that all conditions in City VI. were 
favorable save that examinations were given only by the teacher, 
(2) that in City VII. the examinations were given by the teacher 
and perfunctorily by the superintendent, while (3) in City I. the 
superintendent, with the principals, took pains in setting the tests. 
It seems probable that the cause he alleges is a real one, though 
even his own facts show the cooperation of other causes. This 
I take it he does not mean to deny. 

The fourth sample of studies of the influence of the environ- 
ment is not of major importance, but is distinctive in that its facts 
cannot be accounted for by any force other than the environment. 
The facts are the changes in the careers of scholarly college 
graduates from the class of 1840 to that of 1895, comprising 5283 
members of the honorary society, B K, admission to which 
was substantially a recognition of superior scholarship in college. 

The four professions, law, medicine, teaching and the ministry, 
have, together, attracted almost exactly the same proportion of 
scholarly men in each decade. The per cent oi B K gradu- 
ates entering some one of these four professions was 65 in 1840- 
59, 65!/^ in 1860-69, 65 in 1870-79, and 64 in 1880- 1894. 

Among the professions, however, there have been marked 
changes, as shown in Table 16. In twenty years the law doubled 
its attractiveness to scholarly men and then, in half that time, 
lost two-thirds of its gain. Medicine was, in the last decade of 
the period, becoming more attractive. The table shows a very 
rapid rise in the popularity of teaching from 1840 to i860 and 
again from 1870 to 1895, The years from '60 to '65 show an 
opposite tendency. The law was then gaining rapidly and the 
ministry was holding its own. The most striking change was 
the decrease in the proportion of scholarly men making the min- 
istry their life work. The decrease would be even more marked 
if those who entered the ministry but gave up its regular work 



The Influence of the Environment 135 

for that of teaching were included. The incomplete records avail- 
able in the d) 5 Z" Catalogue of 1900 give only 53^ per cent of 
clergymen amongst those graduating from '95-'99 ; and even with 
later additions the per cent for 1900 is probably under 10. 

Roughly, it may be said that three-fourths of the scholarly 
young men who entered the ministry in 1850 would have gone into 
teaching or the law if they had happened to be born a half century 
later. The same original natures choose differently because the 
social and intellectual environment has changed. 

TABLE 16. 
Percentages of Scholarly Youths Making Their Life Work That of : — 

Law Medicine Teaching Ministry 



1840 — 1844 


14 




■ 




9 


4 


37-5 


1845—1849 


10 


■ 


6 


11 


6 


40 


1850 — 1854 


9-3 




13 


7 


36.5 


1855—1859 


10 


5 






16 


4 


34-5 


i860 — 1864 


15 


2 




5-5 


17 


2 


275 


1865 — 1869 


19 


7 




4 


13 


9 


28.5 


1870 — 1874 


19 


8 




5-5 


16 


4 


22.5 


1875—1879 


22 


5 




4 


17 


6 


22 


1880—1884 


16 


4 




4-5 


21 


4 


195 


1885—1889 


14 


4 




7-5 


25 


5 


16 


1890 — 1894 


19 






7 


25 


4 


14 



The near future will doubtless see a rapid increase in the num- 
ber and improvement in the quality of studies of the environmental 
causes of individual differences in mental traits. Rice's investi- 
gation of the differences due to different features of administra- 
tion and teaching has been followed by similar studies by Corn- 
man [02], Stone ['08], Courtis ['09], and Thorndike ['10]. 
Experts in education are becoming experimentalists and quanti- 
tative thinkers and are seeking to verify or refute the established 
beliefs concerning the effects of educational forces upon human 
nature. Students of history, government, sociology-, economics, 
ethics and religion are becoming, or will soon become, quantitative 
thinkers concerning the shares of the various physical and social 
forces in making individual men differ in politics, crime, wealth, 
service, idealism, or whatever trait concerns man's welfare. 

But for the present the exact answers to such questions are 
lacking and all that can wisely be offered is a general statement 
of how outside forces do act upon original natures so as to make 
them more alike or more different than they would otherwise be. 



136 Educational Psychology 

The Method of Action of Differences in Environment 

We may summarize the methods whereby diflferent environ- 
ments act upon intellect and morals as : — 

1. Furnishing- or withholding the physiological conditions for 
the brain's growth and health. 

2. Furnishing or withholding adequate stimuli to arouse the 
action of which the brain is by original nature or previous action 
capable. 

3. Reinforcing some and eliminating others of these activi- 
ties in consequence of the general law of selection in mental life.* 

According to this description we should look upon the mental 
life of an individual as developing in the same way that the 
animal or plant kingdom has developed. As conditions of heat 
and food-supply have everywhere been the first requisite to 
and influence on animal life, so the physiological condiiions of 
the brain's activities are the first modifiers of feeling and action. 
As the stimuli of climate, food, unknown chemical and electrical 
forces and the rest have been the means of creating variations in 
the germs or of stimulating to action the inner tendency of the 
germs to vary, and so have rendered possible the production of 
millions of different animal types, so the sights and sounds and 
smells of things, the words and looks and acts of men, the uten- 
sils and machinery and buildings of civilization, its pictures and 
music and books, awaken in the mind new mental varieties, new 
species of thoughts and acts. In a score of years from birth the 
human mind, like the animal world, originates its universe of mental 
forms. And as, in the animal kingdom, many of these variations 
fail to fit the conditions of physical nature and die after a genera- 
tion or two, so in any one of us many of the mental forms pro- 
duced are doomed to a speedy disappearance in consequence of 
their failure to fit outside events. The elimination of one species 
by others in the animal world is again paralleled by the death 
of those thoughts or acts which are out of harmony with others. 
Species of thoughts, like species of animals, prey upon one another 
in a struggle in which survival is the victor's reward. Further, 

*In all animals capable of profiting by training any act which in a given 
situation brings satisfaction becomes thereby more closely associated with 
that situation, so that when that situation recurs the act will recur also. 
An act that brings discomfort becomes dissociated from the situation and 
less likely to recur. 



The Influence of the Environment 137 

just as species of animals fitted to one environment perish or 
become transformed when that environment changes, so mental 
forms fitted to infancy perish or are transformed in school life ; 
mental forms fitted to school life perish in the environment of 
the workaday world ; and so throughout the incessant changes 
of a mind's surroundings. In mental life resulting pain or dis- 
comfort is the cause of the extinction of a species. The condi- 
tion of a man's mind at any stage in its history is then, like the 
condition of the animal kingdom at any stage in the history of 
the world, the result not only of the new varieties that have ap- 
peared, but also of a natural selection working upon them. The 
tale of a human mind's progress is the tale of the extinction of 
its failures. Possibility of existence, stimuli to variations, selec- 
tion by elimination: these words that describe the action of the 
environment on animal life are equally competent to tell the 
record of a human life. 

The influence of any environmental agency, physical or social, 
varies with its avoidability. Oligarchies lose in influence if there 
is a democracy to which men may emigrate. Customs do not 
make men so infallibly if there is a radical party, however small, 
which ofifers an alternative mode of life. Music's charms to 
soothe obviously are not so universal if men can close their ears. 
A creed loses authority as soon as one disbeliever seeks converts. 
Social environments, institutions, beliefs and modes of behavior 
are nearly omnipotent when undisputed ; for to be the first man to 
revolt means either that one is a mere eccentric and so sure to 
be a failure, or that one is a genius and so very rare. But once 
a revolt is started and advertised, it may much more easily attract 
those whose original natures it fits. And they may be the more 
attracted by it for having been exposed to the opposite force. So 
a given environmental force may even act as a stimulus toward 
just the opinions, interests or acts that it is designed to thwart. 

There are many differences in thought and conduct which are 
nearly equally tolerated by all original natures. To wear a hat 
or not to wear a hat, to express requests and opinions in English 
or to express them in German, to learn astrology or to learn the 
Ptolemaic astronomy or to learn the Copernican astronomy — to 
all original natures these are nearly indifferent issues. Which is 
done depends almost exclusively on environment. In general this 
is true of all the ' whats ' of knowledge and technique. Hozv 



138 Educational Psychology 

many and how hard things a man can learn or do are largely de- 
cided by original nature, but, within these limits, zvhat he learns 
or does is largely a matter of what he is stimulated to do and 
rewarded for doing. On the other hand, there are many features 
of original nature each of which acts to produce nearly the same 
efifect in spite of such differences in outside forces as different 
men can meet in modern civilized countries. In such countries 
it seems possible for any one to be a poet, or to be a political leader, 
or to be a money-maker, if his nature so orders. Original nature 
in general is not irrepressible, and no form of it is absolutely 
irrepressible ; but some forms of original nature seem to be nearly 
irrepressible by any of the environments a man in this country is 
likely to have. 

The Relative Importance of Original Nature and Environment 

It is impossible at present to estimate with security the relative 
shares of original nature, due to sex, race, ancestry and accidental 
variation, and of the environment, physical and social, in causing 
the differences found in men. One can only learn the facts, in- 
terpret them with as little bias as possible, and try to secure more 
facts. This interpretation is left to the student, but with certain 
cautions in addition to or in amplification of those already 
explained. 

Many of the false inferences about nature versus nurture are 
due to neglect of the obvious facts : — that if the environments are 
alike with respect to a trait, the differences in respect to it are 
due entirely to original nature ; that if the original natures are 
alike with respect to a trait, the differences in respect to it are 
due entirely to differences in training ; and that the problem of 
relative shares, where both are effective, includes all the separate 
problems of each kind of environment acting with each kind of 
nature. Any one estimate for all cases would be absurd. 

Many disagreements spring from a confusion of what may be 
called absolute achievement with what may be called relative 
achievement. A man may move up a long distance from zero 
and nevertheless be lower down than before in comparison with 
other men : absolute gain may be relative loss. One thinker may 
attribute differences in achievement almost wholly to nurture 
while another holds nature to be nearly supreme, though both 



The Influence of the Environment 139 

thinkers possess just the same data, if the former is thinking of 
absokite and the latter of relative achievement. The commonest 
error resulting is that of concluding from the importance of sex 
and ancestral heredity that education and social control in general 
are futile. On the contrary, as I have elsewhere said, such studies 
as those of chapters III, IV, and V merely prove the existence of, 
and measure certain determinants of, human intellect and charac- 
ter and demonstrate that the influences of the environment are 
differential, the product varying not only in accord with the en- 
vironmental force itself but also in accord with the original nature 
upon which it operates. We may even expect that education 
will be doubly effective, once society recognizes the advantages 
given to some and denied to others by heredity. That men have 
different amounts of capacity does not imply any the less advan- 
tage from or need of wise investment. If it be true, for example, 
that the negro is by nature unintellectual and joyous, this does not 
imply that he may not be made more intelligent by wiser training 
or misanthropic and ugly-tempered by the treatment he now 
receives. It does mean that we should be stupid to expect the 
same results from him that we should from an especially intel- 
lectual race like the Jews, and that he will stand with equanimity 
a degree of disdain which a Celt would requite with dynamite and 
arson. 

To the real work of man for man, — the increase of achievement 
through the improvement of the environment, — the influence of 
heredity offers no barrier. But to the popular demands from edu- 
cation and social reforms it does. For the common man does not 
much appreciate absolute happiness or absolute betterment. He 
does not rejoice that he and his children are healthier, happier and 
more supplied with noble pleasures than were his ancestors of a 
thousand years ago. His complaint is that he is not so well off 
as some of those about him ; his pride is that he is above the com- 
mon herd. The common man demands relative superiority, — to 
be above those of his own time and locality. If his son leads 
the community, he does not mind his real stupidity ; to be the 
handsomest girl in the county is beauty enough. Social discon- 
tent comes from the knowledge or fancy that one is below others 
in welfare. The effort of children in school, of men in labor and 
of women in the home is, except as guided by the wise instincts 
of nature or more rarely by the wisdom of abstract thought, to 



140 Educational Psychology 

rise above some one who seems higher. Thus the prizes which 
most men really seek are after all in large measure given or 
withheld by original nature. In the actual race of Ufe, which is 
not to get ahead, but to get ahead of somebody, the chief determin- 
ing factor is heredity. 

But the prizes which education ought to seek are all within 
its power. The results for which a rational mankind would strive 
are determined largely by mankind itself. For the common good 
it is indifferent who is at the top, — zvhich men are achieving 
most. The important thing for the common good, for all men, 
is that the top should be high — that much should be achieved. 
To the absolute welfare of all men together education is the 
great contributor. 

Another caution is not to make false inferences about moral 
responsibility from the fact that individual differences are in large 
measure due to nature ; nor to use such false inferences to discour- 
age acceptance of evidence in support of this fact. 

It is from time to time complained that a doctrine which re- 
fers mental traits largely to original make-up, and consequently to 
ancestry, discourages the ambitions of the well-intentioned and 
relieves the world's failures from merited contempt. But every 
one is agreed that a man's free will works only within limits, and 
it will not much matter for our practical attitude whether those 
limits are somewhat contracted. If the question is between orig- 
inal nature and the circumstances of nurture it is rather more 
encouraging to believe that success will depend on inherent quali- 
ties than to refer it entirely to advantages possessed during life, 
and contempt is merited more by him who has failed through 
being the inferior person than by the one who has failed simply 
from bad luck. Whether or not it is merited in either of the 
two cases we shall decide in view of our general notions about 
merit and blame, not of our psychological theories of the causes 
of conduct. 

On the whole it seems certain that prevalent opinions much 
exaggerate the influence of differences in circumstances and train- 
ing in producing the intellectual and moral differences found in 
men of the same nation and epoch. Certain natures seem to have 
been made by certain environments when really the nature already 
made selected that environment. Certain environments seem to 



The Influence of the Environment 141 

eliminate certain traits from an individual when really they merely 
expel the individual in toto. 

Thinkers about the organized educational work of church, 
library and school need especially to remember three facts. 

First. — For the more primitive and fundamental traits in hu- 
man nature such as energy, capability, persistence, leadership, 
sympathy and nobility the whole world affords the stimulus, a 
stimulus that is present well-nigh everywhere. If a man's origi- 
nal nature will not respond to the need of these qualities and the 
rewards always ready for them it is vain to expect much from 
the paltry exercises of the schoolroom. 

Second. — The channels in which human energy shall proceed, 
the specific intellectual and moral activities that shall profit by 
human capacities, are less determined by inborn traits. The 
schools should invest in profitable enterprises the capital nature 
provides. We can not create intellect, but we can prevent such a 
lamentable waste of it as was caused by scholasticism. We can 
not double the fund of human sympathy, but we can keep it 
clear of sentimental charity. 

Third. — Morality is more susceptible than intellect to environ- 
mental influence. Moral traits are more often matters of the 
direction of capacities and the creation of desires and aversions. 
Over them then education has greater sway, though school educi- 
tion, because of the peculiar narrowness of the life of the school- 
room, has so far done little for any save the semi-intellectual 
virtues. 

The one thing that educational theorists of to-day seem to 
place as the foremost duty of the schools — the development of 
powers and capacities — is the one thing that the schools or any 
other educational forces can do least. The one thing that they can 
do best is to establish those particular connections with ideas which 
we call knowledge and those particular connections with acts 
which we call habits. 



CHAPTER VIII 

The Nature and Amount of Individual Differences in 

Single Traits 

For the purpose of the following discussion, let a ' single trait ' 
be defined as one whose varying conditions in men can be meas- 
ured on one scale. A combmation of traits requires two or more 
scales. For example, in so far as the difference between John 
and James in reaction time to sound can be measured as so many 
thousandths of a second on one scale, reaction time to sound is a 
single trait. The difference between John and James in tempera- 
ment, on the contrary, can be stated only in terms of several 

scales, such as quick slow, intense superficial, 

broad narrow, and the like. So temperament is to be re- 
garded as a combination of traits. 

Individuals may be compared with respect to one trait at a 
time, or with respect to certain combinations of traits. We natur- 
ally take up first the simpler case. 

The most desirable description of the differences between in- 
dividuals in a mental trait would be to give the facts for all hu- 
man beings,* then for all of each sex,* then for all of each race 
and of one sex,* and so on for each stock, degree of maturity, and 
kind of training. That is, the condition of the individuals in each 
of a great many groups, each defined by sex, ancestry, age and 
training, would be described. By combining these one could de- 
scribe the condition of the individuals in groups defined by sex 
and age alone, or race and age alone, or race, age and training 
alone, and the like. 

For practical reasons, however, the individuals whose differ- 
ences one from another have been measured often form groups 
of a somewhat adventitious character. For example, the indi- 
vidual differences between one student and another in university 
classes in psychology have been measured, because such classes 

*That is for a random sampling of them. 

(142) 



Individual Differences in Single Traits 143 

are at the psychologist's service. So also " college freshmen ", 
or " children of a certain school grade ", or " those who are will- 
ing to reply to a series of questions sent out by mail " are groups 
determined by convenience rather than by significance. 

The group is often deliberately narrowed, as when the indi- 
viduals are all insane, or all intellectually deficient, or all morally 
delinquent, or all men of science. 

Furthermore, many of the facts concerning individual differ- 
ences came as by-products of investigations of general mental 
laws or of group differences. For example, the early investigators 
of the least noticeable difference, of the time required for a simple 
reaction or for a reaction with discrimination, of the range of 
consciousness and the like, often considered the divergences of 
single men from the average of all men as " errors " due to chance 
conditions. These investigators took no interest in these individ- 
ual divergences save as annoying hindrances to the exact formu- 
lation of constant laws of mental life. So also students primarily 
interested in the differences of man from woman have, without 
desire, got results concerning the differences of one man from 
another. 

Finally the experiments made for us by the general conditions 
of life often provide data concerning the differences of individuals 
within a group constituted by some very complex circumstances. 
The differences of teachers in respect to salary, of college gradu- 
ates in respect to general achievement in life, or of criminals in 
respect to the number and nature of their convictions by courts 
of law are samples. 

As a result, there does not exist any study of the differences 
of a random sampling of all human beings in a single mental 
trait ; or of a random sampling of individuals of the same sex ; or 
of individuals of the same sex and age. There are, however, stud- 
ies of the differences of a random sampUng of individuals of the 
same sex and approximately the same age and race. The boys 
12 years o months to 13 years o months old found in the schools 
of a German or English town would form such a group, and such 
boys have been measured with respect to certain mental traits. 
There are also studies of individuals of the same sex and of nearly 
the same age, race, and training (in certain particulars). The 
children just mentioned, if limited to a given grade or standard 
in school, would be thus nearly alike in respect to school training. 



144 



Educational Psychology 



In spite of the difficulties of interpretation that arise from the 
mixture of unknown degrees of age, race and training, four gen- 
eral facts about individual variations in traits taken one at a 
time seem highly probable, (i) The variations are, in general, 
greater in acquired than in original traits. (2) They are, in 
general, greater in traits peculiar to man than in traits character- 
istic of all mammals. (3) The variations are usually, perhaps al- 
ways, continuous. One grade or degree or amount is not sepa- 
rated from the next as ten men is separated from eleven men, but 

TABLE 17. 

The Abilities op 37 Adult Women Students in Adding, after One 
Hour's Special Practice. Time Required (in Seconds) to Add 48 
Single Columns Each op 10 Figures Taken at Random from the 
Series 2-9. 50 Per Cent of the Time for One Column Was Added 
FOR Each Wrong Sum. 



























ni 




rt 




oi 




a 




a! 




rt 




3 




3 




3 




3 




3 




3 




3 




3 
> 


4-> 


> 


4-^ 


12 


4-' 


IS 


4-) 


> 


■i-t 
























.— < 




^ 




< 


•0 
C 


X3 
< 


•0 
a 
1— 1 


JO 

< 


a 
>— 1 


1 


a 
I— ( 


3 
< 


a 


240 


h 


390 





465 


V 


508 


c 


669 


J 


845 


b 


242 


1 


428 


P 


482 


w 


535 


D 


719 


K 


896 


c 


249 


1 


433 


q 


488 


X 


545 


K 


729 






d 


267 


k 


437 


r 


489 


y 


550 


F 


741 






e 


272 


1 


459 


s 


499 


z 


572 


G 


763 






t 
i 


290 


m 


463 


t 


504 


A 


628 


H 


772 






g 


315 


n 


464 


u 


506 


B 


642 


1 


811 







TABLE 18. 

The Abilities op 37 Adult Women Students in Drawing Lines to Equal 

100 MM. Lines: Average Error (in mm.) from the Stand.'vrd. 















•— < 












c3 




a 




nj 




rt 




ai 




rt 




3 




3 




3 




3 




3 




3 




> 




r2 




3 


4-' 


-a 

> 


>. 

■^-t 


•d 
> 




'd 




























c 


J3 
< 


3 




3 

HH 


< 


C 
hH 


J2 


C 

hH 


< 


•0 
3 

hH 


X! 
< 


I 


■9 


8 


2.0 


15 


2.8 


22 


3-4 


29 


4-9 


36 


9-1 


2 




3 


9 


2.2 


16 


2 


9 


23 


3 


7 


30 


5 


2 


37 


10. 2 


3 




5 


10 


2.3 


17 


2 


9 


24 


3 


8 


31 


5 


5 






4 




6 


II 


2.4 


18 


3 


I 


25 


3 


9 


32 


5 


9 






5 




8 


12 


2.6 


19 


3 


I 


26 


4 


2 


33 


6 









6 




8 


13 


2.7 


20 


3 


3 


27 


4 


4 


34 


6 


7 






7 




9 


14 


2.7 


21 


3 


4 


28 


4 


6 


35 


7 


3 







Individual Differences in Single Traits 145 

as ten pounds is separated from eleven pounds. (4) The varia- 
tions usually cluster around one central tendency or " type." 

Sample Surfaces of Frequency of Single Traits 

As a preliminary to the discussion of these Laws of Mental 
Variations I present in Tables 17 and 18 and Fig. 26 samples of 
measurements of groups of individuals in traits taken singly. 

From these tables one can calculate the amounts of difference 
existing and the relative frequency of each. For example, in 
Table 17 it appears that the two most unlike individual? of 37 
chosen at random from women students of education differed 
by 656 seconds (896-240) in adding 48 examples, or by 13^ 
seconds per example. Differences of 12 seconds or over per ex- 
ample (576 seconds or over for 48 examples) occurred 11 times 



I II Ml I II I III illil il III I ! I 11 III 

800 m m m w m m 



I I I I II III II Mini III |u II I \ 

I^A 10 W 1) Iq Sfl Hf} 3S IS )0. 

Fig. 26. (Upper Diagram). The ability of each of 37 women in adding. 
The scale gives the time in seconds required to add 48 single columns, each 
of 10 figures, 50 per cent of the time for one column being added for each 
wrong sum. Each vertical line represents one individual. 

Fig. 26. (Lower Diagram). The ability of each of 37 women in draw- 
ing lines to equal a 100 mm. line. The scale gives the average deviation in 
millimeters from the standard. Each vertical line represents one individual. 

(between each of individuals a, b, c, and d and each of individuals 
J and K; also between each of individuals e, f and g and indi- 
vidual K) ; etc., etc. The median of all the individual differences 
will be found, by any patient reader who cares to compute it, to 
be about 33^ seconds per example. The median of the deviations 
of the 37 individuals each from 11 seconds per example, which is 
the central tendency of adult women students of education in this 
trait, is 2.2 seconds per example. 
10 



146 Educational Psychology 

The Amounts of Difference in Different Traits 

Any such measurements of the frequencies of different degrees 
of difference between one individual and another or between indi- 
viduals and some central tendency or type, are not, however, read- 
ily commensurate except within the same trait. To the question, 
" Do these women differ more in ability to add than in ability 
to accurately equal a length of 100 mm?," the answer is: — The 
range of difference is 13^ seconds in one case, (5 to i8f), 9.1 
millimeters in the other ; the median difference is 3.5 seconds 
(approx.) in one case and 1.8 millimeters (approx.) in the other; 
the median deviation from the central tendency is 2.2 seconds 
in one case and 1.2 millimeters in the other. 

Now in common speech, and in books on psychology and edu- 
cation as well, the differences between two individuals in two or 
more mental traits are compared. Such statements as, " John 
differs little from James in memory, and much in judgment," or 
" Men are much more alike in sense powers than in imagery," are 
made. If they are justifiable, the differences in different traits must 
somehow have been made commensurate. 

In particular, my statement concerning the variations in original 
versus acquired traits, or in mammalian versus distinctively hu- 
man traits, must depend upon some means of comparing the mag- 
nitudes of variations in different traits. 

In comparing the tallest and shortest of 100 adult men, we 
can say, not only that they differ by, say, 20 inches, but also (sup- 
posing them to be 76 and 56 inches) that the tallest is one and five 
fourteenths times as tall. In comparing the wealth of the men 
we can say not only that one has $10,000 more, but also that (sup- 
posing them to possess $1,000 and $11,000) he is eleven times as 
rich. In a certain real and useful, tho limited, sense, it can 
be said that adult men differ more in wealth than they do in 
weight, and more in weight than they do in stature. The ratio 
of the difference of one man from absolute zero, or just not any 
amount of the thing in question, to the difference of another man 
from the same zero or just-not-ness is in a sense commensurate with 
a similar ratio in the case of another thing. Nothingness is taken 
to be the standard and ' just not any ' of one thing is treated as 
equivalent to ' just not any ' of another thing. 

If one wished to use the test in addition to place a person on a 



Indhndual Differences in Single Traits 147 

scale for " ability in addition " one would find no such clear and 
sure way to make the judgment of " times as far from o 
ability." It would be very hard to define " ability to add which 
is just barely not no ability to add " in terms of any test's score. 
It would be still harder, if not impossible, to define it in terms of 
a score in this test. Should it be 100 sec. per example, or 1000, 
or 10,000, or 100,000, or infinity? 

If one wished to use the test in drawing lines to place a person 
on a scale for ability to notice differences he would have not 
quite so hard a task. For there would be some reason for taking, 
as o ability, a divergence of 100 mm., — that is, failure to distin- 
guish from the standard a line of zero length. 

There is great absurdity in common opinions of what " just not 
o " is in the case of a mental trait and of what the relative differ- 
ences between this and that manifestation of the trait and o are. 
Even gifted and well trained thinkers will assert, some that the 
best handwriting is only one and a half times as " good " as a 
nearly illegible scrawl, and some that it is eight or ten times as 
good. They will declare, some that the average man knows twice 
as much as the average dog, and some that he knows a thousand 
times as much. Some of them will assert, on finding that one 
boy spells 48 words correctly out of a list of 50 and another 6, 
that the former was thereby proved to be eight times as good a 
speller. Even if we should all study somewhat exhaustively the 
logic of the " times " judgment in mental traits, there would still 
be fairly wide disagreements concerning, say, how many times 
as much curiosity the most curious man had than the average man 
or than the least curious man ; or concerning how many times as 
much mathematical knowledge the most learned mathematician had 
than the stupidest idiot. 

But by any rational and just decision as to what ' o ' or ' just 
not anything ' was for each mental ability, we should find abun- 
dant evidence of the truth of the two laws — that individual differ- 
ences in single traits are greater in acquired than in original abili- 
ties ; and that they are greater in abilities peculiar to man than in 
abilities possessed by mammals in general. 

For example, suppose that we regard as absolute zeros, the 
following: just not any A's marked in a minute, just not any 
sums correctly given in a minute, just not any dots placed in a 
series of squares, and the like, using as the measure in every case 



148 Educatiottal Psychology 

the amount done of some task, some amount of which nearly all 
adult Americans can do. The ' times as much ' then comes out 
greater for thought than for movement, greater for memory of a 
passage than for memory of unrelated words or numbers, greater 
for responding to the meanings of words than for responding to 
the differences of colors, greater for marking words containing 
both a and t than for marking A's amongst other letters, greater 
in solving problems in arithmetic, mechanical difficulties, or geo- 
metrical puzzles than in sorting out colors. 

For the reasons stated at the beginning of this chapter a survey 
of the data bearing on the comparative variability of man in dif- 
ferent traits would not be desirable, even apart from the difficulty 
of choosing zero points. Moreover, the truth of the statement that 
as a rule individuals differ more in acquired than in original traits 
hardly needs statistical proof. The range of variations or the 
average individual difference is obviously greater in the acquired 
perceptions of words, music, geometrical forms and the like than 
in the original sensitivities to colors, sounds or distances ; in the 
acquired movements of writing, sewing, singing and the like than 
in the original reflexes and instincts of winking, swallowing, 
clasping, running or striking ; in knowledge, which is largely ac- 
quired, than in movement, which is to a considerable extent orig- 
inal ; in the interests in literature, science or politics than in the 
interest in sex. 

Within a narrow group, of course, uniformity of conditions may 
occasionally act to reduce natural differences, for example in habits 
of eating. But if men are taken over all the world and over a 
number of centuries it is hard to find any trait where the modifi- 
cations by training do not increase natural differences. 

The second law, that variations are greater in traits peculiar to 
man than in traits common to man and the mammals in general, 
is evidenced by the comparison of variability in remembering 
ideas with variability in remembering acts of skill, by the com- 
parison of variability in marking A's with variability in marking 
logically absurd sentences, by the comparison of variability in 
drawing a line between two lines accurately with that in defining 
a word accurately, and the like. As the superiority of the best to 
the worst philosopher is greater than that of the best to the 
worst rememberer of places or avoider of animal enemies,. 



Individual Differences in Single Traits 149 

so the variability in thinking with ideas in general is greater than 
that in the simple sensori-motor processes. 

The Continuity of Mental Variations 

Continuity of variations means two things, — the absence of 
regularly recurring gaps, such as those between 2 petals, 3 petals, 
4 petals, and the like, and the absence of irregularly recurring gaps, 
such as those between mice and rats, between rats and squirrels, 
and the like. 

That continuity* of variations in a mental trait taken singly is 
the rule can best be realized by trying to find exceptions to it. 
Such there may be, but I am not aware that any mental trait 
varying in amount has been shown to vary by discrete steps. A 
misleading appearance of regularly recurring gaps often arises 
from inadequate measurements. In a test of memory, for example, 
12 nonsense syllables being read, individuals may appear in the 
scores as 5, 6, 7, 8 and 9 without any 5.5's, 6.75's and the like. 
But if four such tests are made and the average is taken, there 
will be 5.5's and 6.75's. 

A misleading appearance of irregular discontinuity often arises 
from the insufficient number of cases measured. If only a few 
individuals are measured in a trait or if the scale is a fine one, 
there will of course be divisions on the scale or amounts of the 
trait unrepresented in any individuals. Thus in Fig. 26 (p. 145) 
there are such gaps, which would all have been filled in, had the 
number of individuals been very large. The 37 individuals whose 
abilities were reported in Fig. 26 were, in fact, chosen at random 
from 200. If all the 200 records had been used in constructing 
Fig. 26, its gaps would have been largely filled in. For example, 
the 37 cases show, between the abilities 500 and 700, a distribution 
as in the upper surface of Fig. 27, whereas the 200 cases show, 

*0f course continuity is not taken here in the sense of infinite 
divisibility. There are doubtless ultimately unit-factors which either act 
or do not act, and which consequently increase the amount of the trait 
by either zero or a certain amount. But the discrete steps are exceedingly 
small like the steps of increase of physical mass by atoms. Intelligence, 
rate of movement, memory, quickness of association, accuracy of discrimina- 
tion, leadership of men and so on are continuous in the sense that mass 
amperage, heat, human stature and anemia are. 



ISO 



Educational Psychology 



over the same extent of the scale, a distribution as in the lower 
surface of Fig. 27. 

It should be unnecessary to warn the reader against the 
absurdity of deliberately changing continuous variations into a 
few groups by coarse scaling ; next assuming that the central part 
of one of these coarse divisions really measures all the individuals 
therein ; and finally imagining that, because the continuous series, 
varying from a to a + b, has been called, say, Poor, Medium, Good 



600 



500 



.600 



500 



Fig. 27. The distribution of the cases falling between 500 and 700 
seconds in adding 48 columns each of 10 one-place numbers, when, in all, 
37 individuals were measured (upper diagram) ; and when, in all, 200 
individuals were measured (lower diagram). 

and Excellent, there are really gaps within it ! Unfortunately 
even gifted thinkers are guilty of this error. 

The Relative Frequencies of Different Amounts of Difference 

The question of the clustering of variations around one central 
tendency demands more elaborate treatment. Fig. 28 shows the 
relative frequencies of the different amounts of the trait in the 
case of six mental traits. These six distributions illustrate the 
statement on page 145 that ' variations usually cluster around one 



Individual Differences in Single Traits 



151 




n 




A 



D 






B 





C F 

Fig. 28. Samples of the forms of distribution found in mental traits. 

A. Reaction time : 252 college freshmen. 

B. Memory of digits : 123 women students. 

C. Efficiency in marking A's on a sheet of printed capitals : 312 boys from 

12 years months to 13 years months. 

D. Efficiency in giving the opposites of words : 239 boys from 12 years 

months to 13 years months. 

E. Accuracy in drawing lines to equal a 100 mm line : 153 girls from 

13 years months to 16 years months. 

F. Efficiency in marking words containing each the two letters a and t : 

312 boys from 12 years months to 13 years o months. 
In all six cases the left end of the scale represents the lowest abilities, — 
that is, the longest times in A, the fewest digits in B, etc. The continu- 
ous lines give the distributions. The broken lines are to be disregarded for 
the present. 



152 



Educational Psychology 



central tendency.' This statement is not, however, universally, or 
even commonly, accepted. On the contrary the common opinion 
is that the distribution of individuals with respect to the amount 
of a single trait is multimodal, as in Fig. 29A, or even a compound 
of entirely distinct species, as in Fig. 29B. There would then be 
many small differences and many large differences with few cases 
of medium differences. This may be called the ' multiple type ' 






A 



V 



B 



Fig. 29. Multimodal distributions. 



theory. For instance, in the case of intellect we find the terms 
genius, normal, feeble-minded, imbecile and idiot used as if the 
geniuses were separated by a clear gap from the normal 
individuals, these again from the feeble-minded, and so on. So 
also visualizers and non-visualizers, or men of normal color vision 
and the color blind, are spoken of as if those in each group were 
all almost identical and all much unlike all in the other growp. 

Multimodality is to be expected in traits the amount of which 
may be greatly increased or decreased by some one cause (or 



Individual Differences in Single Traits 153 

number of causes commonly acting together). If, for instance, 
reading Aristotle added enormously to anyone's intellectual gifts, 
we should expect to find men divided into two distinct surfaces 
of frequency on a scale for intellect, the higher ranking species 
being made up almost exclusively or even entirely of those who 
had taken the Aristotelian dose. The action of ophthalmia in 
causing blindness in the new-born is such a cause. By reason of 
it and other diseases, the visual capacity is reduced enormously 
in certain individuals, so that there are two modes, the seeing 
and the blind. Fewer men are able just barely to see than are 
totally blind. Injury to the head at birth or disease of the 
thyroid gland may be such a cause, reducing certain individuals 
all to an equal condition of intellect, so that possibly, by reason 
of it and other accidents and diseases, the number of very idiotic 
children may be greater than the number of those less idiotic 




Fig. 30. A distribution showing a secondary type, of great inferiority. 

over an equal length of the scale (see Fig. 30). This is doubtful, 
however. 

In certain traits, such as knowledge of a certain language, or 
ability to play a certain game, there are two species. One includes 
those who have had no opportunity to get the knowledge or 
ability and whose knowledge or ability is consequently o ; the other 
is made up of those who have had some opportunity to get the 
knowledge or ability and who range in it from o or near o to a 
large amount. Understanding of spoken English, or ability to 
play chess or whist or golf, or ability to typewrite or to navigate 
a ship by the compass, would, of course, give such groups, if 
measured in adults the world over. Here the cause does not 
produce a uniform amount of the trait, but the world is so 
arranged that on many persons the cause does not act at all. 

Many such causes may act in the case of particular habits. 



154 



Educational Psychology 



knowledges and skills. Since, for example, some Germans are, 
and some are not, subjected to the action of enforced military 
service, there may well be two modes to the surface of frequency 
of knowledge of the manual of arms, one group all knowing it very 
well, the other group knowing hardly anything about it. Appren- 
ticeship to a certain trade, or enrollment in a certain kind of school, 
may thus lead to extreme and uniform amounts of knowledge of, 
say, plastering or typewriting or medicine, so as to divide human 
nature sharply into an ordinary and an expert class. How far this 
happens is not known. 



Fig. 31. Relative frequencies of different amounts of efficiency in mark- 
ing A's on a printed sheet of capital letters, in the case of a group of 
twelve-year-olds, boys and girls together. 

If sex made a great enough difference in the amount of any 
trait, there would be two modes in the surface of frequency for 
the trait in question in the two sexes combined. But observable 
bimodality as a result of mixture of the sexes does not in fact 
appear, because the sex differences are so small. For example, 
Fig. 31 shows the result of such mixture in one of the traits in 
which the sexes differ most. Figs. 32 and 33 show the distribution 
separately for each sex. 

In traits in which race makes a great difference there will tend 
to be a mode for each racial type if two extreme races are mixed. 
Fig. 34 shows the results of so mixing civilized Europeans with 
Negritos (Figs. 35 and 36 giving the separate distributions for 
Europeans and Negritos). But if all races, or a random selection 
of races, were mixed the resulting surface of frequency would not 
show a distinct mode for each, or probably for any one. Even 



Individual Differences in Single Traits 



155 



so great a difference as that between the whites and the colored 
in scholarship in the high school is shown in the combined dis- 
tribution only by a flattening of the surface of frequency as 
compared with that of either race alone (see Fig. 37). 



Fig. 32. Relative frequencies of different amounts of efficiency in mark- 
ing A's on a printed sheet of capital letters, in the case of twelve-year-old 
boys. 



Fig. 33. Relative frequencies of different amounts of efficiency in mark- 
ing A's on a sheet of printed capitals, in the case of twelve-year-old girls. 

In traits in which age makes a great difference, there will be 
a marked flattening of the surface of frequency. Thus, whereas 
for any one age, say 10 years and 7 months, the variations with 
respect to ' School Grade Reached ' will cluster closely around one 
grade, the distribution for individuals of all ages from 8 years 
through 14 years, shows three almost equally frequent degrees of 



iS6 



Educational Psychology 



34 



































1 






















,. ... _ . _ 1 



17 27 37 



36 



7 17 27 37 



36 



7 17 27 37 

Figs. 34, 35 and 36. Relative frequencies of different times required to 
insert variously shaped blocks in holes to match. The best abilities (that 
is, the shortest times) are at the left end of the scale in each case. Fig. 34 
gives the distribution for a group equally divided between vi^hites and 
Negritos. Fig. 35 is for whites alone. Fig 36 is for Negritos alone. 



Individual Differences in Single Traits 



157 



the trait. This fact is shown in the case of the boys of one large 
city in Fig. 38. 

The common opinion that there are distinct species of 
individuals, with more or less pronounced gaps between, does not, 
however, limit itself to presupposing such multimodalities as those 
made by men and women, by Germans and Bushmen, by five-year- 
olds and fifteen-year-olds, by the ordinary population and the blind 
in respect to vision, by plumbers and non-plumbers in respect to 



r^ 



Fig. 37. The relative frequencies of different degrees of high-school 
scholarship in a group composed of 150 whites and 150 negroes. The 
lowest grade of scholarship is at the left, the highest grade at the right, end 
of the scale. 

skill in plumbing, by those who never tried to learn chess and 
those who did, in respect to ability at playing chess, and the like. 
It knows little or nothing of the effect of various combinations of 
causes upon the form of distribution of a trait and it thinks of 
men as divided off into sharp classes in mental traits chiefly 
because it has not thought properly about the question at all. It 
merely accepts the crude adjectives and nouns which express 
primitive awareness of individual differences, as representatives of 



158 



Educational Psychology 



L_ 
















1 2 3.4 6 «.7 8 9 10 

Fig. 38. The relative frequencies of differ ent degrees of progress in 
school in the case of boys 8 years o months to 14 years 11 months inclusive. 
The horizontal scale at the bottom is for 'grade reached,' i, 2, 3, etc., mean- 
ing first grade, second grade, third grade, etc. The surfaces of frequency 
are, in order from the top down, for 8-year-olds, 9-year-olds, lo-year-olds, 
ii-year-olds, 12-year-olds, 13-year-olds, 14-year-olds, and 8-14-year-olds 
combined. 



Individual Differences in Single Traits 



159 



corresponding divisions in reality ; neglects the existence of inter- 
vening grades ; and does not even attempt to estimate the 
frequencies grade by grade. How strong this tendency to verbal 
thinking is can be beautifully illustrated by the firm conviction of 
even long-trained men of science that people are either markedly 
right- or markedly left-handed, are either ' normal ' in color vision 
or far removed from the ' normal ' in color weakness or color 



A 



B 

Fig. 39. The distortion of the form of distribution due to the presence 
of too few cases. A is the distribution as found from several hundred 
cases ; B is that found in the same trait from the first 28 of them. 

blindness. Until recently the superstition that a great gulf separ- 
ated children of normal intellect from the imbeciles and idiots was 
also very strong in many scientific men. The multiple-type theory 
does not refer to the separation of individuals into groups by the 
presence or absence of some one cause, or closely interrelated 
group of causes. It simply vaguely fancies that individuals, even 
of the same sex, race, age and training, somehow naturally fall 
into distinct classes or ' types.' 



i6o Educational Psychology 

In such a form it is surely almost always, if not always, wrong. 
A group of such individuals does not, as a rule, show a separation 
into two or more groups, all in one being much like each other 
and little like any of those in the other group, or groups. Here 
again the rule may be verified by searching for exceptions to it. 
I know of no such. The misleading appearance of such may come 
either (i) from inadequate measurements, as in the case of the 
pseudo-discrete variations, or (2) from the examination of an 
inadequate number of individuals. Thus ( i ) if men are rated, for 
sensitiveness to red and green, as color blind, color weak and of 
' normal ' color vision, there will appear to be three types, just as 
there will appear to be three types of stature if all men are rated 
as short, medium or tall. But in careful tests the color blind will 
vary among themselves, the color weak likewise and the ' normal ' 
likewise ; the color blind will merge imperceptibly into the color 
weak and these into the ' normal.' Thus (2) if only fifty 
individuals are measured and if the scale is arranged so that these 
are included by, say, twenty divisions of it, there is a fair 
probability that, though the distribution of a thousand individuals 
show a clustering around one type as in Fig. 39A, the fifty 
may be clustered around two or more types as in Fig. 39B. The 
absurdity of inferring the existence of two species of human 
nature with respect to a trait from two apparent modes found 
when only a few individuals are studied should be obvious. 

The Chance or Probability Distribution in the Case of Single 

Mental Traits 

In sharp contrast to the common notion that human beings are 
divided sharply into classes, is the theory that, for any one trait, 
men, at least by original nature, form always only one class defined 
by one single sort of distribution. This theory answers in the 
affirmative the questions : " Do the distributions of mental traits 
in groups of individuals follow any regular law? Are the differ- 
ences between individuals in mental capacities and characteristics 
amenable to any single type of description?" It supposes that, 
in all original traits, human beings so differ as to make the 
distribution that of a chance event, the surface of frequency being 
that of the probability integral. The exact meaning of this sup- 
position and the basis for it need not now be discussed. Our present 



Individual Differences in Single Traits 



i6i 



interest is in discovering how far any one type of distribution does 
characterize all original mental traits in human beings. By using 
graphic representations rather than algebraic formulae, the answer 
and the evidence for it can be made clear even to one who knows 
nothing whatever of the mathematical properties of the surface 
of frequency of a chance event or of any other. 

Fig. 40 gives the distribution or surface of frequency of the 
type to which by this theory the distributions of natural abilities 





Figs. 40 and 41. The 'chance' or 'probability' form of distribution. 



conform. Fig. 41 gives the same distribution as Fig. 40, but with 
a coarser separation into grades. 

Before comparing actual distributions with this theoretical form 
of distribution it will be profitable to inquire somewhat more 
systematically into the relation between the factors which deter- 
mine the amounts of a trait in an individual and the relative 
frequencies of its different amounts among men. 

Suppose the amount of a trait to be determined by six causes or 
factors — a, b, c, d, e, and f — each contributing i toward it; and 
suppose that each individual's nature includes a chance drawing 



II 



i62 Educational Psychology 

from these causes, any combination being equally likely to be 
drawn. 

The possible combinations are : — 

None 

a b c d e f 

ab ac ad ae af be bd be bf cd ce cf de df ef 

abc abd abe abf acd ace acf ade adf aef bed 

bee bcf bde bdf bef cde cdf cef def 

abed abce abcf abde abdf abef acde acdf acef 

adef bcde bcdf beef bdef cdef 

abcde abcdf abcef abdef acdef bcdef 

abcdef 

Consequently for every individual possessing o units of the 
trait there will be 6 possessing 6 units of it, 15 possessing 2 units, 
20 possessing 3 units, 15 possessing 4 units, 6 possessing 5 units, 
and I possessing 6 units. The relative frequencies of the different 
amounts of the traits will be : — 



Amounts of 


Relative frequencies 


the trait. 


of these amounts. 





I 


I 


6 


2 


15 


3 


20 


4 


15 


5 


6 


6 


I 



Fig. 42 shows the form of distribution graphically. 

Suppose that instead of six such causes there were twenty. The 
results of chance drawings from the possible combinations would 
then be to give, for every individual possessing o units of the trait, 
20 possessing i unit, 190 possessing 2 units, 1140 possessing 3 
units and so on, as in Table 19 and Fig. 43. 

Suppose the number of causes to be increased, the other condi- 
tions remaining as before. The relative frequencies would assume 
more and more closely the proportions shown in Fig. 40 (p. 161), 
which is the surface of frequency of an event caused by a chance 



Individual Differences in Single Traits 163 

TABLE 19. 

Form of Distribution Resulting from Random Combina- 
tions OF 20 Causes of Equal Magnitude 

Amounts of Relative frequencies 



the trait. 


of these amounts 





I 


I 


20 


2 


190 


3 


1,140 


4 


4,845 


5 


15,504 


6 


38,760 


7 


77,520 


8 


125,970 


9 


167,960 


10 


184,756 


II 


167,960 


12 


125,970 


13 


77,520 


14 


38,760 


15 


15,504 


16 


4,845 


17 


1,140 


18 


190 


19 


20 


20 


I 



selection from among the combinations of a large number of fac- 
tors each of small and all of equal amount. This surface is 
bounded by the probability curve. It is often called, or miscalled, 
the ' Normal ' surface of frequency or ' Normal ' distribution 

The distribution of individuals in certain anatomical traits is 
much like that of Fig. 40. The close fit of individual variations 
in stature and the like to the particular bell-shaped surface of the 
probability integral naturally led to the expectation, or at least 
the hope, that all variable facts in original human nature would 
vary in this one way. In particular, individuals of the same sex, 
age, race and training should form a true species and vary in 
this one way. 



164 



Educational Psychology 



As a matter of fact they do not, but they approximate it. No 
one form of distribution fits them all, but the bell-shaped curve 
given by the equation y=e-^^ fits them better than any other 
simple curve. Fig. 28 (p. 151) gives fair samples of the closeness 
of fit in mental traits.* The condition of an individual in a trait 
is very often the result of something approximating a chance 
selection of one out of many combinations of many factors, each 
of small and nearly equal influence on the trait's amount. In so 



48 



43 



Fig. 42. The 'chance' form of distribution from six equal and indepen- 
dent causes. 

Fig. 43. The 'chance' form of distribution from twenty equal and 
independent causes, 

far as it is so, the relative frequencies of the different conditions 
of individuals in respect to the trait will be approximately those 
of the so-called ' Normal ' surface of frequency. But just as 
there cannot be two or more sharply defined types unless there 
are certain large causes whose presence makes a great diflference 
in the trait's amount, so there cannot be a very close approximation 
to the ' Normal ' sort of distribution unless the causes are nearly- 
independent, and of nearly equal influence. 

*The broken lines in Fig. 28 give, in each case, the ' chance ' form of 
distribution. 



Individual Differences in Single Traits 165 

Such a trait as stature shows approximately the probability dis- 
tribution, because its amount in any individual is determined by 
many only slightly correlated causes, such as the thickness of the 
skull, height of various bones of the head, thickness of each 
of the vertebrae, length of each of several bones in the leg, and 
the like. Each of these causes is again determined by very many 
imperfectly correlated causes. But such a trait as ' wealth pos- 
sessed ' will not. For certain relatively very large causes are at 
work, such as the discovery of a mine, or the death of rich rela- 
tives; and there is a strong correlation between many of the 
causes, for instance, between success in a business, directorship in 
a bank, advanced knowledge of important actions, and power to 
influence these actions. 

" The form of distribution is then purely a secondary result of 
a trait's causation. There is no typical form or true form. There 
is nothing arbitrary or mysterious about variability which makes 
the normal type of distribution a necessity, or any more rational 
than any other sort or even any more to be expected on a priori 
grounds. Nature does not abhor irregular distributions. 

On a priori grounds, indeed, the probability curve distribution 
would be exactly shown in any actual trait only by chance. For 
only by chance would the necessary conditions as to causation be 
fulfilled. And, in point of fact, as the reader has constantly been 
told by the adjective ' approximate,' the exact probability curve 
distribution does not appear in the facts or give signs of being 
at the bottom of the facts of mental life. The common occurrence 
of distributions approaching it is due, not to any wonderful tend- 
ency of a group of cooperating causes to act so as to mimic the 
combinations of mathematical quantities equal and equally prob- 
able, but to the fact that many traits in human life are due to 
certain constant causes plus many occasional causes largely un- 
related, small in amount in comparison with the constant causes 
and of the same order of magnitude among themselves." [Thorn- 
dike, '04, p. 69 f.] 

Distributions approximating it do occur very commonly in 
mental traits of original nature. And one will probably never be 
far misled by supposing that, in respect to the amount of original 
endowments in any trait, individuals of the same sex, race and 
age are distributed approximately according to the probability 
surface. The evidence from measurements points toward such 



i66 



Educational Psychology 



approximation. Moreover, what is known of the physical basis 
of intellect and character leads to the expectation that many 
somewhat nearly equal factors are at work to determine the 
amount of any instinct or capacity possessed by men. 

The meaning of some of the cases where the distribution of 
mental traits does not approximate the chance distribution will 
become clear if we examine, first, some cases of the distribution 
of a trait in a group of individuals of two or more distinct degrees 
of maturity or of training, and, second, cases where some selective 



X ^ 



I 



i-T_r-i 



dK 





r£ 



46 47 

Figs. 44-47. The effect upon the form of distribution due to combining 
groups distinct in respect to age, training or some other cause affecting the 
trait in question. 

Fig. 44. The distribution of ability, in the A test, of children 8, 9, 14 
and 15 years old. 

Fig. 45. The distribution of abiHty, in the opposites test, of children 
from grades 3 and 7. 

Fig. 46. The distribution of ability, in muhiplication, of children from 
grade 7 and high school. 

Fig. 47. The distribution of ability, in the a-t test, of children 9 and IS 
years old. 

agency has been at work. Fig. 44 gives the distribution of ability 
in the A test in a group of children 8, 9, 14 and 15 years old. Fig. 
45 gives the distribution of ability in writing the opposites of 



Individual Differences in Single Traits 



167 





te- 



r^^-^ 



2A 




kl 



1 K 








1 






1 1 







h 



54 

Figs 48-54. The effect upon the form of distribution due to the 
selection of individuals in relation to causes affecting the amount of the 
trait in question. The left end of the scale is for the lowest degree of the 
trait in each case. 

Fig. 48. The distribution of ability, in controlled association, of 12-year- 
old boys in the 6A grade or higher. 

Fig. 49. The distribution of ability, in controlled association, of 12-year- 
old boys in the 6B grade or lower. 

Fig. 50. The distribution of ability, in controlled association, of all 
12-year-old boys in the school. 

Fig. si. The distribution of ability, in mathematics, of candidates for 
honors in mathematics at Cambridge University. 

Fig. 52. The distribution of ability, in marking A's, of university teachers 
and students. 

Fig. 53. The distribution of ability, in memory, of university teachers 
and students. 

Fig. 54. The distribution of ability, in giving the opposites of words, of 
inferior day-laborers. 



i68 Educational Psychology 

words in a group composed of about 140 girls in the third school 
grade and about 180 girls in the seventh school grade. Fig. 46 
gives the distribution of ability in multiplication in a group com- 
posed of seventh grade pupils and high school pupils. Fig. 47 
gives the distribution of ability in marking words, containing 
each the two letters a and t, in a group comprising 9-year-olds and 
15-year-olds. In general when the surface of frequency of a 
mental trait departs from the probability curve toward a flatten- 
ing and toward the appearance of two or more modes, one may 
expect to find a mixture of sexes, races, ages or trainings. 

Fig. 48 gives the distribution in a test of controlled association 
of the 12-year-old boys in the 6A grade or higher. The lack of 
symmetry in the surface is obviously due to the fact that we are 
dealing with a selected group — that the duller and less mature 
boys have been eliminated. The influence of the opposite sort of 
elimination is seen in Fig. 49, which gives the distribution, in the 
same trait, of 12-year-old boys in the grades lower than the 6A. 
By combining the two we have Fig. 50, which approximates the 
chance distribution. Fig. 51 gives a real case of a distribution dis- 
torted by selection. It is the distribution of mathematical ability 
in the candidates for honors in mathematics at Cambridge JJniver- 
sity.* Of course such candidacy implies that the poorer grades 
of mathematical ability are eliminated. Figs. 52 and 53 represent 
the distribution of ability, in marking A's and in immediate memory 
of lists of words respectively, in seventeen university teachers and 
students, while Fig. 54 represents the distribution of ability in 
the ' opposites ' test in the case of twenty day-laborers of inferior 
sort. Any selective agency which works upon a species of indi- 
viduals will alter the shape of the surface of frequency for any 
mental trait, unless its selections are random with respect to dif- 
ferent amounts of that trait. As the selective action is commonly 
such as picks out the good or the bad, the result is commonly to 
produce a ' skewness ' of the surface toward one extreme and a 
blunted condition at the other. When a series of measurements 
in a group of the same sex, age and training shows a deviation 
from the probability surface toward conditions like those of Figs. 
55 and 56, it is wise to ascertain whether some selective agency 
has not been at work upon the group. 

We have seen that the form of distribution of a single mental 

*It is taken from Galton's Hereditary Genius, 26. ed. p. 16. 



Individual Diiferences in Single Traits 169 

trait is usually such that the individuals cluster around one cen- 
tral tendency. We have seen also that, within a group of the 
same sex, race and age, in original traits, the variations from 
the central tendency occur in approximately the relative frequen- 
cies described by the probability distribution. A deviation of any 
degree plus is about as common as that of the same degree minus ; 
or, more briefly, the distribution is approximately symmetrical. 
The average, median and mode therefore nearly coincide. The 
frequency decreases with the amount of deviation from the cen- 
tral tendency, at first slowly, then rapidly and then slowly. The 





Figs. 55 (above) and 56 (below). 

average deviation from the central tendency is about 1.18 times 
the median deviation. About 82 per cent of the individuals differ 
from the C. T. by less than 2 times the median deviation ; about 
96 per cent by less than 3 times the median deviation ; about 99/^ 
per cent by less than 4 times it. 

The most important fact, however, is not the commonness of 
this or that form of distribution, but the absolute law that the 
form of distribution is a result of the nature of the factors at work 
to produce the trait's amount. One large factor that is present 
for some individuals and not for others will always act toward 
the production of bimodality or distinct types. A multitude of 
nearly equal factors from which each man's nature and training 



170 Educational Psychology 

is approximately a random selection will always act toward the 
production of unimodality, symmetry, and slow-rapid-slow de- 
crease in frequency around the central tendency. An interde- 
pendence whereby the action of certain factors increasing the 
amount of the trait is dependent upon the action of other factors 
which of themselves bring the individual to a certain fairly high 
station, will always act to disturb symmetry. For every peculiar- 
ity in the causes determining a trait's amount in an individual 
there will be an effect in the relative frequencies of the trait's 
amounts in a group of individuals. 

I should perhaps apologize to the reader for this long discus- 
sion of a matter which may seem to be sufficiently obvious with- 
out any discussion. I am glad if it does now seem obvious. The 
excuse for the long discussion is that the usages of language have 
persistently misled thinkers about human nature into supposing 
that it was, in each trait, divided into sharply separated classes to 
fit the adjectives and nouns by which primitive man roughly de- 
noted different sections of a continuous scale, and that, on the 
other hand, certain thinkers have carelessly extended the particu- 
lar ' probability ' form of distribution to cases where it cannot 
possibly fit the facts. 



CHAPTER IX 

The Relations Between the Amounts of Different Traits 

IN THE Same Individual 

One feels a bareness and paltriness in such piecemeal descrip- 
tions of human beings and their differences one from another as 
have been given in the last chapter. The actual varieties of hu- 
man nature do not stand out when one trait at a time is measured. 
Why, it may be asked, does psychology not take actual whole na- 
tures and state how they differ? Why does psychology not de- 
scribe human minds as zoology describes animal bodies, by classi- 
fying them into families, genera and species, and by stating the 
differences between the different sorts of minds found? 

It is true that zoology does not measure all animals in length, 
then in weight, then in color, then in number of organs, then in 
number of bones, and so on through a list of particular traits. It 
began with types or sorts apparent to common observation, such 
as worms and fishes, and described their essential features and 
the characteristic differences of one sort from another. And it is 
true that psychology might try to do likewise. If there were types 
or sorts of minds equally apparent to common observation, it 
would surely be worth while to start a description of human na- 
ture's varieties with them. But there are no sorts or types of 
minds that stand out clearly as birds, fishes and worms do amongst 
animal forms.* Psychology has first to find which the sorts or 
types are. 

There are two ways of discovering them. The first is by direct 

*The men allied by common ancestry, men of the same race, would be 
most likely to form a mental sort or type diflfering from other men, if not 
as fishes differ from other animals, at least as much as salmon differ from 
other fishes. But even between races there is no surety that such is the 
case and no excuse for avoiding the slow and laborious comparison of 
individuals from different races in one after another trait that seems 
significant. 

(171) 



172 Educational Psychology 

measurement of individuals in toto, and of their differences. To 
measure the difference between one whole man and another 
means to assign to each man his amount of each trait, and to 
measure each difference. The difference between the two men 
means just all those particular differences. To this method we 
shall return in the next chapter, though it may be said at once 
that no adequate total measurements exist of even a single indi- 
vidual. 

The second way of discovering the sorts or types into which 
men as total natures are divided is by discovering what each 
amount possessed of any one trait implies concerning the individ- 
ual's condition in other traits. 

A statement of the differences between one whole man and 
another would be an almost interminable inventory of particular 
differences, unless some traits were so related that knowledge of 
the amount of one of them possessed by a man informed us of the 
amount he possessed of the other also. Suppose, for instance, that 
any given amount of error in judging one length with the eyes 
always implied certain known amounts of error in judging all 
lengths, whether by eye, by arm-movement or by pressure, all 
weights, all colors, all pitches, all tastes, all smells, all bright- 
nesses, all intensities of sound and all other sensory features of 
objects. In such case, one measurement would inform us, once 
for all, of a fairly large fraction of a man's nature and of his 
differences from another man, similarly measured. The necessary 
preliminary to the direct study of differences of total natures is 
thus the study of the relations of single mental traits. 

The Measurement of Relations between Mental Traits 

It is necessary to be clear at the outset in respect to just what is 
meant by the relation, or, as it is commonly called, the correlation, 
between two mental traits. It means, of course, the relation of 
some amount of one trait (A) to some amount of another trait 
(B). It also means, for the present purpose, the relation between 
an amount of A characteristic of a given individual to an amount 
of B characteristic of that same individual. The amounts might 
be the amount of A more than zero and the amount of B more 
than zero; or they might be the amount of A more than, or less than, 
some assigned amount and the amount of B more than, or less 



Relations Between Mental Traits 173 

than, some assigned amount. Let us call the first sort relations of 
divergences from and the second part relations of divergences 
from arbitrary standards, or arbitrary relations. 

For example, suppose 5 eight-year-old girls, I, II, III, IV and V, 
in tests of memory of German equivalents of English words, to 
show the following abilities : — 

Trait A Trait B 

Median number of words Median number of words 

remembered (after a given remembered (after a given 

amount (K) of training) amount (K) of training) 
' 2 minutes. at the end of 60 days. 

II 

II 

9 

3 
5 

In the first meaning, the relation of the divergence from zero 
is, of course, expressed as |^, ^, yV, ^ and f , respectively 
for these children. The central tendency of the relation is, 
roughly, to remember half as much after two months as was 
remembered after two minutes. 

Suppose, now, that the relation sought is that between 
divergence from the central tendency for eight-year-old girls in A 
and divergence from the central tendency for eight-year-old girls in 
B, and that this central tendency is 15 for A and 6 for B. The 

w ^u +5+5+3-3 -I 

relations are then -; — ^, - — 7, -; — , and 



Individual 


at the end of 


I. 


23 


II. 


21 


III. 


16 


IV. 


II 


V. 


9 



4-8' +6' -hii' -4 -6* 

Suppose that the relation sought is that between divergence from 

the central tendency of all human beings in A and divergence from 

the central tendency of all human beings in B, and that these central 

tendencies are 24 for A and 10 for B. The relations are then 

, — , — TT, and . It is clear that any relation 

- I ' -3' -8' -13 -15 ^ 

varies according to the standards from which the related diverg- 
ences are measured. 

The relations to be considered in this chapter are arbitrary 
relations. We shall always be concerned with the relation of an 
individual's divergence from the central tendency of some defined 
group in one trait to his divergence from the central tendency of 
that same group in another trait. 



174 Educational Psychology 

The first fact to notice about such mental relations is that the 
same relation varies greatly in different individuals. Such a case 
as that of the last illustration, in which the relations were, for 
five individuals, -i.oo, -.33, +.125, +.54, and +.33, is not at all 
exceptional. The relations of traits differ in individuals as truly 
as do the amounts of a trait. A single sample will suffice. Fig. 57 
shows the relation of (A) divergence from the central tendency 
of adult college women in drawing a line* to equal a 50 mm. line 

-50 -30 -10 +10 +30 +60 +70 +170 

-90 • , • 

-70 

-60 . 

-80 ♦ . 

-10 

+ 10 . , 

+30 .: ' • . 

+50 

+^70 * ' . 



Fig. 57. The relation between ability in equalling a 50 mm. line (average 
of 30 trials) and ability in equalling a 100 mm. line (average of 30 trials), 
in women students. 

to (B) divergence from the central tendency of the same group 
in drawing a line* to equal a lOO mm. line. Each dot represents 
the relation in one individual by its location. Each dot is below 
the point (on the scale for A) which is the individual's measure 
in A and opposite the point (on the scale for B) which is the 
individual's measure in B. 

*Under certain specified conditions. 



Relations Between Mental Traits 175 

It is at once seen that superiority of an individual to the central 
tendency of adult college women in A does in general imply 
superiority to their central tendency in B, but that there is a 
wide range in the relation in individual cases. If the relation had 
been the same in all individuals, the dots would all be on one line, 
since all the individuals under any one point of the horizontal 
scale (that is, of the same ability in A) would all be opposite the 
same point of the vertical scale. 

Since the relation does vary with individuals, it is fully measured 
or described only by such a list of all the individual relations as 
Fig. 57 gives. But its main features can be summarized, for any 
one degree of trait A, in two measures, one of the central tendency 
of all these individual relations, and the other of their variability 
around this central tendency. 

Thus, suppose 10 individuals, all -8 in Trait A, to be, respec- 
tively, - 12, - 7, - 5, - 5, - 4, - 4, - 2, - I, o and +6 in Trait 

B. The median of the ratios 3^ , ^7^. ITe"' ^^^- i^ 3^' ^^ 

+ .5. The central tendency of the relation is for - 8A to imply - 4B. 

The variability ranges from an implication of - 12 to one of + 6 

The relation may also vary with different individuals according 

to the amounts of A which they have. Thus, suppose that the 

central tendency in the case of individuals all having +16A was 

— 2 
to the relation q^y^. The + .5 which restated the central tendency 

of the relation for individuals of - 8A, is replaced by -.125. 

Fig. 58 shows a case (hypothetical) of a relation varying much 
with the amount of trait A, but with very little variation amongst 
individuals of like ability in A. 

Fig. 59 shows a case (also hypothetical) of a relation varying 
little with the amount of trait A, but much amongst individuals 
of like ability in trait A. 

Fig. 60 shows a case (also hypothetical) of a relation varying 
much in both respects. 

In these figures the line formed by the points representing each 
the central tendency of the relation in the case of one amount of A 
may be called the relation line. In Figs. 58, 59 and 60, it is the 
line formed by the large dots. 

When a relation varies according to the amount of one of the 
traits, — when, that is, the central tendency of the ratio A/^B 



176 



Educational Psychology 



Amount of Tnit A -H > 



to 



I 



«• » ■ 

• • • 



• •.:• 






• • 









••• •• • •* 

• ♦J 



• . • -• i 






Fig. 58. A relation varying much with different amounts of Trait A, 
but varying little amongst individuals of like ability in A. 

Amount ot Trait A -H >• 



At 

tad 



c 



Fig. 59. A relation varying little with different amounts of A, but much 
amongst individuals of like ability in A. 

is different for A=k, A=2k, A^3k, etc., — it may be called non- 
rectilinear, because the relation line is curved or broken. When 
a relation varies with individuals irrespective of their amounts of 



Relations Between Mental Traits 



177 



Trait A, the central tendency of the A/B ratio being the same 
for all values of A, it may be called rectilinear because the relation 
line will be a straight line. 

When only a few individuals are studied, so that the number at 
any given point on the scale for A is not enough to give reliably 
the central tendency of the relation at that point, the relation will 



Amount of Trdit A 



■> 






w 



V * 



Fig. 60. A relation varying much in both respects. 

Figs. 58-60. The variability of mental relations. 
Trait A is scaled horizontally, the lowest degree being at the left. 
Trait B is scaled vertically, the lowest degree being at the top. 
Each dot represents the relation in one individual, the amount of A 
possessed by the individual being that represented by the point on the 
scale for A above the dot, and the amount of B possessed by the individual 
being that represented by the point on the scale for B at the left of the dot. 
The large dots represent, each by its position, the central tendencies 
(medians) of those of each degree of ability in A. 

appear non-rectilinear even though it may really be rectilinear. 
For example, the relation between ability in the A test and ability 
in the a-t test in 12-year-old boys (divergences from C. T.'s for 
that age and sex being related) is really rectilinear or very nearly 
so, but the relation line for any 100 boys will seem to be much 
broken as in Fig. 61. Whatever be the real form of the relation 
line, chance deviations from that form will appear unless the num- 



12 



178 



Educational Psychology 



ber of cases is infinitely large. But in reality sharply irregular 
relations with zigzag relation lines, — such relations for instance as 
.5for Arr=k, .7for A = k+l, .3for A = k+2, .5forA = k+3, 
.4 for A = k + 4, .6 for A = k+5, .5 for A = k + 6, and so on 
— probably do not exist between any mental traits. 

Relationships with curvilinear relation lines deviating markedly 
from straight lines, — such as that in Fig. 58 or those in Fig. 62, — 
may exist, but no such relation has as yet been proved to exist. 
It is therefore customary to treat relations between mental traits 
as approximately rectilinear. 

The relation of two traits in a given group of individuals being 
expressed as the rectilinear relation which best fits them, their 
relation can be compared with that of any other traits in the same 
or any other group — provided one more simplification be made. 




A-T 
-6 



-10 -8 -6 -4-2 0+2+4+6 +8 +10 +12 +14 

Fig. 6i. The relation line in the case of the relation between ability in 
marking A's (one trial of 6o seconds) and ability in marking words con- 
taining both a and t (one trial of I20 seconds), in the case of girls of the 
same school grade. (With more adequate tests the relation would be much 
closer and the relation line somewhat straighter.) 

This is that the divergences to be related be expressed each as a 
fraction of the variability of the trait in question. For example, 
suppose A, B, C and D to be series of divergences, in height, 
weight, memory of words in a certain test, and ability in the A test, 
from the condition of the modal twelve-year-old boy. Suppose 
that the central tendencies of the ratios A/B, A/C and A/D 
were respectively .5, .2 and .5. That would mean that a boy ten 
centimeters above the central tendency would in the long run be 
5 kilograms heavier, remember 2 words more, and mark 5 A's 



Relations Between Mental Traits 



179 



more, than the modal twelve-year-old boy. This does not enable 
one to tell whether A/B is really equal to the relation A/D, 
though each is .5. Nor can one say with any useful meaning that 
A/^B is two and one-half times as close a relation as A/C. 




Fig. 62. Samples of curvilinear relation lines. 



But if, instead of calculating the gross A/B, A/C and A/D 
ratios (.5, .2 and .5), we calculate the values of these ratios after 
every value of A is expressed as a multiple of the variability of 
twelve-year-old boys in trait A, every value of B is expressed as 



i8o Educational Psychology 

a multiple of the variability of twelve-year-old boys in trait B and 

so on, the ratios become commensurate. 

Suppose the variabilities of twelve-year-old boys in the four 

traits to be, respectively: — Var. A, 4.5 centimeters; var. B, 3.5 

pounds ; var. C. 2.0 words ; var. D, 4.5 A's. Then the central 

, , . A /var. A A/var. A , A/ var. A .„ 

tendencies of the ratios, =-—^ -, =r— ^ ^ and .pr =: , will 

BXvar. B C/var. C D/ var. D 

be .4, .09 and .5.* The .4, .09 and .5 will, in each case, mean the 

same thing, if 'equal multiple of the variability' of any one trait 

is regarded as always the same thing. They will mean, in each 

case, the relation of (I.) an individual's divergence in one trait 

measured as a multiple of the general tendency to diverge in that 

trait, to (II.) his divergence in another trait, measured Hkewise 

as a multiple of the general tendency to diverge in that trait. 

It is with such a meaning that we compare the closeness of the 
relation between, say, memory for numbers and memory for 
words with the closeness of the relation between memory for the 
same data over a short and over a long interval ; or compare either 
of these with the relation between accuracy of discrimination of 
length and accuracy of discrimination of weight. 

If each divergence is expressed in terms of the variability of 
its trait as a unit,we can think of an individual's condition in one 
trait as resembling or differing from his condition in another 
trait. The technique of measuring this resemblance between two 
traits in one man is then the same as that m.ade familiar in Chap- 
ter V in the case of the resemblance of two individuals in the 
same trait. R, the coefficient of resemblance, then measures the 
central tendency to resemblance or mutual implication found in 
pairs of amounts or conditions in two traits, each pair being 
characteristic of an individual. The amounts are divergences 
from the central tendencies of some defined group. The relation 
or resemblance or mutual implication is supposed to be constant 
for all amounts of either trait. R is a figure so calculated from 
the individual records as to give the one degree of relationship 
between the two traits which will best account for all the sepa- 
rate cases in the group. In other words it expresses the recti- 
linear relation from which the actual cases might have arisen with 

* A ^ var. A _ A var. B ^^ 3j „^ ^ Similarly for the .09 

B -- var. B B ^ var. A ^ ^ 4.5 ^ 

and .5. 



Relations Between Mental Traits i8i 

least improbability. It has possible values from +1.00 through o 
to — i.oo. 'R = +i.oo' means that the individual who is the 
best in the group in one ability will be the best in the other, that 
the worst man in the one will be the worst in the other, that if 
the individuals are ranked in order of excellence in the second, 
the two rankings will be identical, that anyone's divergence 
in the one will be identical with his divergence in the other (both 
being reduced to multiples of the variabilities of the abilities to 
allow comparison). 'R = -i.oo' would, per contra, mean that 
the best person in the one ability would be the worst in the 
other, that any degree of superiority in the one would go with 
an equal degree of inferiority in the other. ' R = + .62 ' would 
mean that (the two series of divergences being reduced to mul- 
tiples of the variabilities in question) any given divergence in the 
one trait would imply, on the average, 62 hundredths as much di- 
vergence in the other. 

Samples of the Interrelations of Mental Traits 

As samples of R's so calculated I give in Table 20 some of 
those obtained by Burt ['09] in the case of 30 boys between 125^ 
and 13^ years of age in an Elementary School in Oxford, at- 
tended by boys ' of the lower middle class ', whose parents paid 
9d. a week tuition. The relations are all between divergences, 
each from the central tendency of the group in the trait in ques- 
tion. The traits were (in part) : — 

Touch. — Delicacy of simultaneous discrimination of two points on the skin. 

Weight. — Delicacy of discrimination of lifted weights. 

Pitch. — Delicacy of discrimination of pitches (from 320 vibs.) . 

Length. — Delicacy of discrimination of length; deviation from the 
standard, 100 mm. 

Tapping. — The number of holes made in 15 sec. in a sheet of paper over 
cloth, a needle fastened in a holder being used. 

Dealing. — The time required to deal 50 cards into 5 heaps in the ordinary 
manner. 

Sorting. — The time required to deal 50 cards into 5 heaps in accordance 
with the color of the cards. An error was not corrected by 
the boy, but was allowed for by an addition to his time- score. 



1 82 Educational Psychology 

Alphabet Sorting. — 52 cards, each 20 mm. square and printed with a letter, 
each letter appearing twice in the series, were exposed in an 
irregular order. The boy was required to find a, then to find 
b, then c, etc., placing them in order in two rows. He then 
repeated this selecting again. The time taken was the score. 

Immediate Memory. — Of 90 words (30 concrete, 30 abstract, and 30 non- 
sense) all of one syllable, each one seen and pronounced by 
the boy, given in series of 4, 5, 6, 7, or 8. For method of 
scoring see Burt, '09, p. 142. 

TABLE 20. 

Thb Interrelations op Nine Mental Traits in the Case of Thirty Boys 

Each Entry Gives the Relation op the Trait Listed on the 

Line to the Lept of the Entry to the Trait Listed 

Above the Entry. Adapted from Burt ('09]. 

Decimal Points are Omitted. 





1 


4-> 

•a 
•53 


J3 
PL. 


a 


Ml 

a 
a 


a 

1 
P 


a 

u 




a 
< 




a 


Touch 




37 


01 


26 


12 


32 


20 


66 


15 


Weight 


37 




06 


—16 


II 


05 


23 


26 


07 


Pitch 


— 01 


06 




—05 


53 


41 


25 


68 


19 


Length 


26 


—16 


—05 




16 


59 


32 


37 


05 


Tapping 


12 


II 


53 


16 




79 


78 


67 


01 


Dealing 


32 


05 


41 


59 


79 




77 


83 


18 


Sorting 


20 


23 


25 


32 


78 


77 




83 


27 


Alphabet 


66 


26 


68 


37 


67 


83 


83 




47 


Memory 


15 


07 


19 


05 


01 


18 


27 


47 





The figures of Table 20 show^ the traits measured by the tap- 
ping, deahng and sorting tests to be so related that the amount 
of any one possessed by a boy gives a fairly close prophecy of 
the amounts that he w^ill possess of the others. The traits meas- 
ured by the tests of discrimination of touches, weights, pitches 
and lengths on the other hand are shown to be highly independent 
one of another. 

Mental relations have been measured by Wissler ['01], Spear- 
man ['04a, '04b, '06], Thorndike ['03, '09], Pearson ['07], 
Brown ['09], Burt ['09], Frost,* Simpson,* and others. The 
results form a body of facts of great importance to psychology 
and education, but a summary of them without elaborate discus- 
sion of the methods used in each case, would be misleading. I 

*In a study as yet unpublished. 



Relations Between Mental Traits 183 

shall, therefore, state only the general conclusions to which they 
lead. 

The Significance of the Relations Between the Amounts of 
Different Traits in the Same Individual 

The significance of the relations between mental traits which 
have been measured in this way is seen most easily and clearly 
by observing the doctrines about individual psychology which 
they disprove. 

First may be mentioned a series of beliefs in mental antago- 
nisms or compensations. Such are : — that superiority to the cen- 
tral tendency in vividness and fidelity of imagery of one sort 
implies inferiority to the central tendency in vividness and fidelity 
of imagery of other sorts; that superior ability to get impres- 
sions through one sense is related to inferiority in getting im- 
pressions through other senses ; that intensity of attention varies 
amongst individuals in opposition to breadth of attention, so that 
a high degree of power to attend to one thing at a time goes with 
a low degree of power to attend to many things at once ; that the 
quick learner is the poor rememberer ; that the man of great artis- 
tic gifts, as in music, painting or literary creativeness, is weak 
in scientific ability or matter-of-fact wisdom ; that divergence 
above the mode in power of abstract thought goes with diver- 
gence below the mode in thought about concrete things ; that 
the man of superior intellect is likely to be of inferior mental 
health ; that the rapid worker is inaccurate ; that an agile mind 
goes with a clumsy body ; etc., etc. 

Not all of these and other supposed antagonisms or inverse 
relations have been specifically tested by the calculation of the 
appropriate R's ; but those which have been so tested have been 
found in gross error. Betts ['09] found the R's for any one sort 
of non-verbal imagery with any other, in respect to vividness, 
completeness and detail, to be not only positive but high. Peder- 
sen's data ['05] show, though he apparently did not notice the 
fact, a very close correlation between ability to grasp presenta- 
tions through the eye and ability to grasp presentations through 
the ear. Meumann ['07] somewhat grudgingly admits that his 
contrast between " men with typically concentrative or intensive 
attention " and " individuals with typically distributive atten- 
tion " ['07, vol. I, p. 500], does not mean that the person who is 



184 Educational Psychology 

superior in the one is inferior in the other ; that, on the contrary, 
he is more Hkely to be superior in the other also (" je grosser die 
Konzentrationsfahigkeit eines Menschen, desto grosser seine 
Distributionsfahigkeit " ['07, vol. I, p. 502 f.] ) The author 
['08] has shown that the individuals who learn a thousand words, 
as in a vocabulary, more quickly than the modal man, also, in a 
majority of cases, remember more of them after 40 days. Cattell 
['03] finds that eminence in artistic lines implies superiority in 
politics or generalship or science more often than the reverse. 
All relevant measurements witness to a positive correlation be- 
tween efficiency in thought with abstract data and efficiency in 
thought with concrete data ; also between the ability to work with 
greater speed at a given accuracy, and the ability to work with 
greater accuracy at a given speed. Indeed the individual who 
works at higher speed often works more accurately at even that 
higher rate than does the slower worker at his more favorable 
rate. 

The relations which do seem to be inverse are very instructive. 
They are mostly cases of the relation of a desirable divergence 
in one trait to an undesirable divergence in the other. Thus 
general intellect seems to be antagonistic to sullenness. Intellectual 
efficiency seems to be antagonistic to emotionality in the crude 
sense. 

It is very, very hard to find any case of a negative correlation 
between desirable mental functions. Divergence toward what we 
vaguely call better adaptation to the world in any respect seems 
to be positively related to better adaptation in all or nearly all 
respects. And this seems specially true of the relations between 
original capacities. 

The negative values in Burt's results, listed above, are probably 
not exceptions to this rule, but are due to the chance variations 
from truth which are to be expected from a small series of 
measures. His -.16 for the relation of discrimination of length 
to discrimination of weight, for instance, should be considered in 
connection with the +.52 obtained by the author ['09] for the 
same relation in the case of 37 young women, and the +.25 
obtained in the case of 25 high school boys. 

There may, however, be cases where some one large environ- 
mental agency acts to bring all those individuals subject to it up in 
one trait but down in another. The Roman Catholic Church 



Relations Between Mental Traits 185 

might thus, at least at certain periods of its history, make many 
of its members more interested in theological argumentation, and 
less interested in scientific verification, than the modal man. The 
theory of asceticism might make all its adherents successful in 
contemplation and inefficient in action. City life might so stimulate 
adroitness in dealing with people and inhibit adroitness in dealing 
with animals and plants, as to produce a negative relation. 
Wherever some potent circumstances act to elevate one trait and 
depress another in individuals subjected to them, whereas alterna- 
tive circumstances act in the opposite direction, there is a chance 
for individuals to show negative R's in the traits in question, 
even though, in original nature, the traits are related positively. 
Such negative relations might appear, if men were measured from 
dififerent national cultures or over thousands of years so as to 
include such contrasting environments, in cases where our present 
measurements show even strong positive relations. 

Little is known about the shares of original mental organization 
and environmental influences in producing the relations of diver- 
gence in one trait to divergence in others, and still less about the 
special effect of what may be called irrational environments, those 
which weaken or inhibit certain generally desirable mental traits. 

Finally, there are the notable cases of apparent compensation 
due to the special practice of one trait to make up for irremediable 
weakness in some other. Keenness of touch in the blind, is, of 
course, the clearest case. Of such cases it may be said that they are, 
for the general relation, trifles, and are partly balanced by other 
cases where special defect and special practice work to the opposite 
eflfect upon the total relation. It should also be noted that in 
original nature the rule is correlation, not compensation. Those 
defective in vision are, by nature alone, more likely to be defective 
in other senses than are those superior in vision. 

On the whole, negative correlations between different 'efficiencies' 
or ' adaptabilities ' or ' desirable traits ' are surely rare, seem almost 
never to occur as a result of original mental nature, and require 
as causes peculiar oppositions of influence upon the two traits from 
the environment. 

A second error in opinions about mental relations is in sharp 
contrast to the one just described. It is the doctrine that some 
one function is shared by all intellectual traits, and that whatever 
resemblances or positive correlations the traits show are due to 



i86 Educational Psychology 

the presence in each of them of this function as a common factor. 
In so far as they have it, they are identical. In so far as they 
lack it, they are totally disparate. In the words of Spearman 
['04 b, p. 84], who advocates such a view, "All branches of intellec- 
tual activity have in common one fundamental function (or group 
of functions) whereas the remaining or specific elements of the 
activity seem in every case to be wholly different from that in 
all the others." 

This doctrine requires not only that all branches of intellectual 
activity be positively correlated, which is substantially true, but 
also that they be bound to each other in all cases by one common 
factor, which is false. The latter would require that no two 
intellectual abilities or branches of intellectual activity should be 
more closely related to each other than to the fundamental func- 
tion by which alone they are supposed to be related ; and, as a 
corollary of this, that no four such abilities, A, B,C,andD, should 
be more closely related in pairs, A to B, and C to D, than the 
element common to A and B is related to the element common 
to C and D. But unless one arbitrarily limits the meaning of ' all 
branches of intellectual activity ' so as to exclude a majority of 
those so far tested, one finds traits closely related to each other 
but with, their common element only loosely related to the common 
element of some other pair. 

The next error may be roughly described as the supposition that 
for any one operation that is the same in form, such as discrimina- 
tion of differences, attention, observation, inference or the like, 
the varieties produced by different data or content are perfectly 
correlated. 

It has been common in psychological and educational literature 
to presuppose that the functions which we group under the same 
name, e. g., attentiveness, somehow implied each other, that, for 
instance, a high status in attentiveness to school work was closely 
related to a high status in attentiveness to social duties, business 
pursuits, mechanical appliances and all the other facts of the 
individual's experience. Our rough and ready descriptive words, 
such as accuracy, thoroughness, reasoning power and concentration, 
have been used as if the quality must be present in approximately 
equal amounts in all the different spheres of mental activity. 
The notion of any special mental act, e. g., the discrimination of 
100 millimeters from 104, has apparently been that some general 



Relations Between Mental Traits 187 

faculty or function, discrimination, was the main component, the 
special circumstances of that particular act being very minor 
accessories. Thus all the different acts in the case of discrimination 
would be very closely related through the presence in them aU of 
this same mental component. 

On the contrary, measurements reveal a high degree of 
independence of different mental functions even where to the 
abstract psychological thinker they have seemed nearly identical. 
There are no few elemental ' faculties ' or forms of mental activity 
which work alike with any and every kind of content. 

For instance, the correlation in adults between ( i ) memory for 
figures and (2) memory for unrelated words (memory being 
used to mean the power to keep a list in mind, after once hearing 
it, long enough to write it down) is not over .8; the correlation in 
pupils of the highest grammar grade between (i) quickness in 
thinking of the opposites of words and of the letters preceding 
given letters of the alphabet and (2) quickness in thinking of the 
sums of figures is not over .7. Yet the first pair of tests would 
commonly be used indiscriminately as tests of ' memory,' and the 
second pair as tests of ' association.' upon the supposition that the 
two members of each pair were practically identical traits. Even 
so apparently trivial a difference as that between drawing a line 
to equal a 100 mm. line and drawing a line to equal a 50 mm. line 
causes a reduction from perfect correlation. The resemblance is, 
for 37 young women students, only .yy. 

A table of the known degrees of relationship would abundantly 
confirm the statement that the mind must be regarded not as a 
functional unit, nor even as a collection of a few general faculties 
which work irrespective of particular material, but rather as a 
multitude of functions each of which involves content as well as 
form, and so is related closely to only a few of its fellows, to the 
others with greater and greater degrees of remoteness. 

The mental sciences should at once rid themselves of the con- 
ception of the mind as a sort of machine, different parts of which 
sense, perceive, discriminate, imagine, remember, conceive, asso- 
ciate, reason about, desire, choose, form habits, attend to. Such 
a conception was adapted to the uses of writers of books on gen- 
eral method and arguments for formal discipline and barren de- 
scriptive psychologies, but such a mind nowhere exists. There 
is no one power of sense discrimination to be delicate or coarse. 



i88 Educational Psychology 

no capacity for uniform accuracy in judging the physical stimuli 
of the outside world. There are only the connections between 
sense-stimuli and our separate sensations and judgments thereof, 
some resulting in delicate judgments of difference, some 
resulting in coarse judgments. There is no one memory 
to hold in a uniformly tight or loose grip all the experiences of the 
past. There are only the particular connections between particu- 
lar mental events and others, sometimes resulting in great surety 
of revival, sometimes in little. And so on through the list. Good 
reasoning power is but a general name for a host of particular 
capacities and incapacities, the general average of which seems 
to the namer to be above the general average in other individuals. 
Modern psychology has sloughed off the faculty psychology in its 
descriptions and analyses of mental life, but unfortunately reverts 
customarily to it when dealing with dynamic or functional rela- 
tionships. 

But it is just in the questions of mental dynamics and of the 
relationships of mental traits that we need to bear in mind the 
singularity and relative independence of every mental process, the 
thoroughgoing specialization of the mind. The mind is really 
but the sum total of an individual's feelings and acts, of the con- 
nections between outside events and his responses thereto, and of 
the possibilities of having such feelings, acts and connections. It 
is only for convenience that we call one man more learned than 
another instead of giving concrete lists of the information pos- 
sessed by each and striking averages from all the particulars ; 
that we call one man more rational than another instead of com- 
paring two series of rational performances. In any one field the 
comparison may give a result widely different from the general 
average. So also with inhibition, concentration, or any other of 
the general names for forms of mental action. 

It is easier to show that mental traits are not related in certain 
ways than it is to show directly just how they are related. There 
are three reasons for this. The first is that, until the work of 
Spearman in 1904, it was not known that any relation, calculated 
from other than complete measurements of the divergences to be 
related, would be reduced from its true amount toward o. Wissler, 
for example, found ['01] the relation between accuracy in 
drawing a line to equal a 100 mm. line and accuracy in bisecting 
it, to be only .38, because he had as measures of the two traits to 



Relations Betzveen Mental Traits 189 

be related only the results with a single line. If each individual 
had been tested with hundreds of lines at different times so as 
to get his real total abilities the result would have been an R of 
.7 or .8. Since this fact of the ' attenuation ' of the R's obtained 
from imperfect original data was not realized at all until 1904, 
and is not realized by many students even now, the majority of 
the R's that have been calculated are of doubtful meaning. For 
only very rarely have the measurements of individuals in any 
trait included many tests on many dates under many circum- 
stances so as to give adequate measures. The true R's can only be 
inferred from the obtained R's by a guess at the degree to which 
the latter are attenuated. In the case just quoted the true R turns 
out twice the obtained ; in other cases it turns out to be only a 
trifle greater, depending of course on the chance deviations of 
the original measures. 

The second reason for our inability to give a clear, simple, 
positive account of the relations of mental divergences is that the 
divergences related have been measured in different groups and 
from all sorts of different central tendencies. The result is that 
many of the relations known are not directly comparable. For 
example R for general scholarship with quality of handwriting is, 
in children in the elementary school, being measured by their 
divergences from the central tendencies of their age and sex, 
about .3. R for general scholarship and desultory memory is, 
certain educated adults being measured by their divergences from 
the central tendencies of graduate students, also about .3. But 
the two relations are really not equal. 

The third reason is that the fact itself would, in any case, be 
too complex for clear and simple positive description. The facts 
which we do know prove that if we knew all the facts the inter- 
relations of mental traits would be irreducible to any easy repre- 
sentation. This is itself, however, an important fact about them. 

Such a general positive description as can be given will be 
best given in graphic form. Let the series of horizontal lines in 
Fig 63 be each a scale for some mental trait ; let the right end 
always represent superiority in the trait ; let the central tendency 
of adult human beings be in each case at the point on the scale 
where a vertical line down the center of the diagram would cut 
the scale. The C. T.'s for all traits are then in a vertical line. 
Let a constant distance always equal the variability of the trait. 



igo Educational Psychology 

Let any one individual be represented by a line joining all the 
points denoting each his ability in one trait. Five individuals 
are thus represented in Fig. 63, in ten traits. If now, instead of 
ten horizontal scales for the traits, there were the thousands 
necessary to inventory human faculty, and if, instead of five 
cross-lines for five individuals, we had thousands representing a 
fair sampling of all men, the picture would show a rough general 
parallelism of the cross-lines corresponding to the general tend- 
ency for efficiency in one trait to go with efficiency in others. 
There would be very few cross-lines from the extreme left of 



Fig. 63. Ten traits shown in their interrelations in the case of each 
of five individuals. Three of the individuals are university teachers or 
graduate students. The other two are inferior day-laborers. 

one scale to the extreme right of the other. On the other hand 
there would be few horizontal lines cut by the same man's cross- 
lines at the same distances from the C. T. There would be many 
cross-lines that departed from the general drift of the cross-lines 
a little ; some that departed from it more ; and a few that departed 
from it enormously. 

The first impression would be of a general parallelism, i.e., 
perpendicularity, of the cross-lines disturbed at haphazard, some- 
what as geological strata are distorted from their parallelisin in 
a mountain region. If, however, one examined the relations, he 
would find certain rough rules for prophesying others. Rela- 
tions would in general be closer within the analytical or abstract- 



Relations Betzveen Mental Traits 191 

ing functions than between these and others. So also within the 
purely mental associative functions like adding, completing words, 
giving opposites, and naming objects, than between one of them and 
one of the sensori-motor functions. The sensitivities would inter- 
relate only loosely ; and any one of them would relate very loosely 
to the associative or analytical functions, even when busied with 
data from that sense. Sensitivity, association, and analysis would 
justify their claims to the title of fundamental forms of mental 
life, by showing closer intra- than inter-relations. The association 
of sense impressions with movement, the association of percepts 
and images as such with one another and with movement, and 
the association of symbols or meaning-carriers such as percepts 
and images of words, would be found to deserve recognition as 
three ' levels ' of mental action for the same reason. Certain 
functions quite diverse from the point of view of the fundamental 
forms of mental life or the ' levels ' of the associative form would 
be found to be related by reason of some instinctive tendency. 
Different degrees of the instinctive interest in persons might thus 
produce correlations between love of ceremonies, ability in sociol- 
ogy and interest in literature. The variations in the love of mental 
activity are one root of many of the correlations between all sorts 
of efficiencies. 

In more detail, the scale for any ability would be cut by a 
cross-line at about the same point that this cross-line cut the scale 
for the corresponding interest ; the scales for sensory and sensori- 
motor powers would be cut by cross-lines in only a loose cor- 
respondence with the scales for ideational controls ; a cross-Hne 
would go far to the right or left as it passed from an ability to 
analyze out intellectual elements to an ability to make a precise 
movement. But the great majority of the details would be blurred 
in the picture by our lack of knowledge. 

Finally the circumstances of training would be seen to some- 
times intensify and sometimes weaken original relations. Thus 
the variations in the length of school training, by connecting a 
long training in certain traits almost inevitably with a long train- 
ing in certain other traits, make certain correlations more pro- 
nounced. The world over, there is a close relation between knowl- 
edge of Latin and knowledge of geometry, far beyond what nat- 
ural interests would produce. 



192 Educational Psychology 

A case of the weakening of an original relation by training 
might be furnished by ability in mathematics and ability in under- 
standing human nature. The original relation is perhaps closer 
than the actual relation in adults, the common forms of training 
tending so often to develop one or the other. 

Roughly the effect of the environment is to make closer the 
relations due to content. A mother comes to observe, attend to, 
and remember her children well ; the plumber ' develops all his 
powers ', as the educational theorists were fond of saying, so far 
as plumbing goes, and neglects them beyond that point ; the 
classical student takes a high position in every formal operation 
when Latin is the datum operated on. 

Just what the original relations are will in the progress of re- 
search be discovered. It is unlikely that the relations of original 
capacities and instincts, including native interests, are so compli- 
cated as the relations amongst adult achievements and abilities. 
But present knowledge is insufficient to determine even the orig- 
inal relations. 



CHAPTER X 

The Nature and Amount of Individual Differences in 

Combinations of Traits : Types of Intellect 

AND Character 

Scientific studies of the natures of individual men in combina- 
tions of traits by the direct method have been very few and 
very inadequate in respect to both the number of individuals and 
the number of traits studied. The measurements of mental rela- 
tions described in the last chapter are the main means of improv- 
ing upon common opinion concerning the varieties of human 
nature in respect to total make-up, or to such large fractions of 
it as are roughly denoted by temperament, mode of thought, 
morals, mental health, manner of work, imagination, and the 
like. 

A Sample Problem: Individual Differences in Imagery 

As a sample of the problems and their treatment we may take 
the natures of individuals in respect to type of imagery, that is, 
in respect to the combination of: — vividness of visual images, 
fidelity of visual images, frequency of visual images, vividness 
of auditory images, fidelity of auditory images, and so on, through 
the list. 

Early in the history of the scientific study of imagery it was 
noted that certain individuals were able to recall in memory pres- 
entations to one sense with a high degree of vividness and fidelity, 
but lacked this power in the case of presentations to some other 
sense. The existence of persons who, for instance, could get 
before the mind's eye vividly and with full detail a mental photo- 
graph, as it were, of a scene, but could not thus reproduce from 
within a melody, an itching nose, or a blow, naturally gave rise 
to the notion of the ' visualizing type.' 

Such cases, of notable ability to get one sort of images and 
notable inability to get other sorts, were then carelessly assumed 
to be the rule. It was supposed that a high degree of vividness, 

(193) 
»3 



194 



Educational Psychology 



fidelity and frequency in images from one sense tended to exclude 
an equally high degree in images from other senses. People were 
called visualizers, audiles, motiles, etc., with the meaning that 
the visualizers had more vivid, faithful and frequent visual images 
than other people and less vivid, faithful and frequent images 
from other senses, and similarly for the audiles, or motiles. In 
graphic form this view would give Fig. 64. 

But the actual examination of individuals showed such ex- 
clusiveness or predominance of one sort of imagery to be the 
exception rather than the rule. To even superficial examination 
it was evident that human natures did not fit into the scheme of 
Fig. 64 at all well. Even those who believed unhesitatingly that 
human natures must be distributed around fairly distinct types 



V- 




T — 



Fig. 64. The interrelations of the degree of development of visual, 
auditory, motor, and touch imagery according to the theory of pure types. 
Imaginary horizontal lines at V, A, M and T are scales for the degree 
of vividness, fidelity and frequency of visual, auditory, motor and touch 
imagery respectively. The lowest degree is in each case at the left. 12 
individuals are represented, each by a line crossing each of the scales at 
the point representing the individual's ability. 

in respect to imagery could not, try as they might, distribute in- 
dividuals around these types. Meumann in fact admits that in 
all his studies of children he never found one such pure type. 
" How rare the pure types [of imagery] are amongst children 
is witnessed by the fact that in our extensive investigations of 
children at Zurich we have never found a perfectly pure type. 
Also I know of no case in the entire literature of the subject in 
which sure proof is given of the existence of a pure type in the 
case of children." ['07, I, p. 494] So new intermediate types, 
such as the auditory-motor, visual-motor, auditory-visual, or even 
visual-auditory-motor-intellectual (!) [Segal, '08], were intro- 



Individual Differences in Combinations of Traits 195 

duced. There the matter remained until Betts ['09] actually 
measured a sufficient number of individuals in respect to the 
vividness and fidelity of non-verbal images from the different 
sense-fields, so that the cross-lines of Fig. 64 could be located by 
fact instead of by opinion. 

The pillars of the doctrine were the separation of men into 
types according to the predominance of images from one sense, 
and the existence of inverse relations between the different 
sense-spheres in respect to the extent and perfection of imagery. 
Fact showed opinion to have been grossly in error as a result 
of its assumption that distinct types of some sort there must be. 
The contrary is true. Instead of distinct types, there is a con- 
tinuous gradation. Instead of a few ' pure ' types or many 
' mixed ' types, there is one type — mediocrity. Instead of antag- 
onism between the development of imagery from one sense and 
that from other senses there is a close correlation. Fig. 65 is a 
fair sample of the facts found. 

This case is instructive because the fate of many theories 
concerning distinct types of human nature in combinations of 
traits is likely to be the same as the fate of the doctrine of types 
of imagery according to the sense involved, with inverse rela- 
tions between the development of imagery from one sense-field 
and that from other fields. In the case of temperament, for 
example, we have the same history. Extreme cases are given 
names and made into types. Verbal contrasts are supposed to 
have real existence. Supplementary types are invented to help 
out the discrepancies between the imagined types and the real 
distribution of individuals. And it is highly probable that, when 
actual measurements are made, mediocrity — a temperament 
moderately sanguine, choleric, phlegmatic, and melancholy ; mod- 
erately slow, quick, shallow, intense, narrow and broad ; moder- 
ately slow-shallow, slow-intense-narrow ; moderately everything, — 
will be found to be the one real type. 

The Theory of Multiple Types and the Single Type Theory 

The sample problem shows well two extreme views which may 
be taken of the varieties of human natures, of the same sex, race 
and degree of maturity, in respect to any combination of traits. 
On the one hand is the theory of multiple types, a theory which 
separates men more or less sharply into classes, and describes a 



196 



Educational Psychology 



man by naming the class to which he belongs. On the other 
hand is the theory of a single human type, a theory which joins 
all men one to another in a continuity of variation and describes a 



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Indkndual Differences in Combinations of Traits 197 

man by stating the nature and amount of his divergences from 
the single type. 

By the theory of a single type, one make-up can be conceived 
such that from it all individuals would differ less than they 
would from any other one make-up, and such that, the greater 
the divergences, the rarer they would be. By the theory of mul- 
tiple types, no such single true central tendency would exist. By 
the theory of multiple types, if a number, K, of ' typical ' natures 
or make-ups are most favorably taken and if divergences of all 
individuals are measured from, in each case, that nature which 
the individual most resembles, the total sum of divergences is 
enormously reduced below what it would be if they had been 




Fig. 66. A graphic representation of the multiple-type theory in the case 
of combinations of traits. The 11 horizontal dotted lines (drawn only at 
the extremes) represent scales for 11 traits. Each cross-line represents, 
by its location, the amounts of the 11 traits in one individual. 



measured all from some one nature. By the theory of a single 
type, this reduction in the sum of divergences due to measuring 
each individual's divergence from any one of K natures, is much 
less. 

These two doctrines can be made clear by graphic illustrations. 
Let the amount of each trait in the combination be scaled, as by 
our custom, horizontally, the center always representing the mode. 
Let the nature or make-up of each individual be represented by 
the points where a cross-line denoting him cuts the scale lines. 
The theory of multiple types then gives something like Fig. 66, 



198 



Educational Psychology 



and that of one type something like Fig. 67. All the cross-lines 
of Fig. 66 can be represented as minor divergences from five 
typical cross-lines, far better than can all the cross-lines of Fig. 
67. Those of Fig. 67 can be far better represented by one typical 
cross-line than can those of Fig. 66. 

A radically different scheme for graphic representation will 
enable the reader to think of the meaning of the two theories for 
a very large combination of traits, say total mental nature. Sup- 
pose that each trait is scaled into 5 amounts, i, 2, 3, 4 and 5. 
Suppose that there are 5 traits, a, b, c, d and e, concerned in the 




Fig. 67. A graphic representation of the single-type theory in the case 
of combinations of traits. The 11 horizontal lines represent scales for 11 
traits. Each cross-line represents the amounts of the 11 traits in one 
individual. 

total complex. Suppose 3 to be the mode in each trait. Con- 
sider every possible cross-line, every possible series of amounts 
in the 5 traits that can be possessed by an individual (but without 
fractionizing any scale farther than into fifths). There will be 
3125 such series possible (5 to the 5th power). Now suppose 
each of these 3125 series of amounts, — each of these 'natures,' — 
to be represented by a spot of, say, .01 sq. in. on a surface. 
Suppose further that the center spot of the map represents the 
series 33333 (the traits being now and later always taken in 
order a, b, c, d and e). Suppose that around this center spot 
and adjoining it are placed all the spots or areas representing 
those series diverging from the 33333 series by only one unit, 
e-g- 23333, 43333. 32333. etc. Suppose that the next ring is 



Individual Differences in Combinations of Traits 199 

made up of the spots or areas representing those series diverging 
from the modal series by two units, e.g. 22^2,2, 43433. 53333, 
etc. Continue till, in the outermost ring, we have areas repre- 
senting the series 55555, iiiii, 11555, 51 115, etc., which have 
the greatest possible divergence from the modal series. 

Now suppose that the relative frequencies with which these 
series appear in men are represented each by the height of a 
column erected with the appropriate area as base. Consider the 
appearance of the resulting relief-map according to the two the- 
ories. By the single type theory, it would be highest over some 
one spot — in our illustration, over the center or 33333 spot.* 
By the multiple type theory, it would have several maxima over 
several spots. By the single type theory, the average height 
would be less and less over each successively more distant con- 
centric ring. The whole relief map would look like a mountain, 
with, possibly, many radiating and cross ridges, casual valleys 
and eminences, but with, always, a decreasing elevation, the 
larger the radius of a circle drawn about the summit. By the 
multiple type theory, the average elevation need bear no rela- 
tion to the distance from the center spot ; the depressions would 
be between the several peaks each representing a type. Tn pro- 
portion as the types were held to be very sharply distinct and 
widely separated, these intervalleys would be deep, even to the 
original surface, and wide. 

Extend now the process of construction of these models to 
thousands of traits each scaled in fifty or a hundred amounts, and 
one has the contrast of the multiple and single type theories applied 
to men's total natures. 

It is not necessary to try to decide between these two theories, 
or to determine just what compromise is the true one. It is bet- 
ter to accept frankly our ignorance of just how individuals do 
differ in combinations of traits until they have been measured 
in respect to all the traits involved. 

But since, in general, writers about human nature openly or 
tacitly assume the truth of the multiple type theory in a pro- 
nounced form, and are governed by it in their methods of re- 
search, of interpretation and of practical control, it will be useful 

*This would be the case in the special form that the theory would almost 
certainly take in the case of combinations of 5 traits, each unimodal, with 
the mode at mediocrity. 



200 



Educational Psychology 



to consider briefly some of the arguments in favor of the single 
type theory. 

The first is the fact that, in proportion as exact measurements 
have been applied, evidence expected to favor the multiple type 
theory has turned out in favor of the single type theory. It is 
true that such cases are very rare, and that, until they are much 
increased in number, little should be inferred from them. But 
the fact remains that the single type theory arose from exact 
measurements, while its opposite came from speculative pre- 
possessions. 

The second is the rarity of the inverse correlations between 
desirable traits upon which so many of the supposed multiple 




Fig. 68. A graphic representation of the condition of individuals in a 
combination of two traits, if these are very antagonistic or inversely 
correlated. The general scheme of the diagram is that used in Figs. 63 to 67. 




Fig. 69. A graphic representation of the condition of individuals in a 
combination of two traits, if these are closely and positively related. 

types are based. We know that eye-minded and ear-minded, 
quick and careful, broad and deep, sensorial and intellectual, men 
of thought and men of action, and the like do not really repre- 
sent human nature's varieties in the combinations referred to. 
If two horizontal scales are drawn for ' ability to learn through 
the eye ' and ' ability to learn through the ear,' and the cross- 
lines are drawn for a thousand individuals, they will not go as 
in Fig. 68 but as in Fig. 69. So also for scales for quantity of 
work and quality of work, and so on through the list. 



Individual Differences in Combinations of Traits 201 

The third is the fact that the single traits involved are so often 
distributed each approximately symmetrically around one mode 
and that their intercorrelations are so often approximately recti- 
linear. In so far as such is the case, no matter what the closeness 
of the correlations may be, the distribution of the individuals in 
respect to the combination of traits will be around one mode or 
peak with less and less frequency the more they diverge from 
that mode. The mode for the combination will be a nature 
which is at the mode in all the single traits. 

The fourth is the fact that investigators who are strongly in 
favor of the multiple type theory and accustomed to interpret 
facts in harmony with it, yet find so few actual cases of it. 
Meumann for instance ['07, vol. I] clearly accepts the theory 
in general and demands that educational practice should give 
much attention to the classification of pupils under distinct types. 
But in concrete particulars he rarely illustrates it. 

He says ['07, vol. I, pp. 331-332] : " By establishing types we 
orient ourselves in the endless possibilities of individual differ- 
ences, and if we can place an individual under a type .... 
in any respect we thereby have pointed out a group of universal 
characters in his mental life, which he in general shares with 
some individuals and by which he is in general distinguished 
from others." But he does not establish such types. The majority 
of the differences which he does report as ' typical ' are differences 
between two extremes of the same trait. Intermediate conditions 
are in some of these cases demonstrably, and in all cases probably, 
more typical than the supposed types. And this, indeed, Meumann, 
in some cases, admits. 

Lastly, I may mention the fact that satisfactory proof of the 
existence of a distribution of human individuals after the fashion 
demanded by the multiple type theory has never been given in 
a single case, and that the evidence offered by even the most 
scientific of the theory's adherents is such as they would cer- 
tainly themselves consider very weak if they were not already 
certain that types of some sort there must be. Thus a fair- 
minded perusal of Stern's Psychologie der Indizdduellen Differ- 
enzen, designed to be a description of the types into which human 
nature falls, is an almost sure means of stimulating a shrewd 
student to the suspicion that intermediate conditions are more 
frequent than the supposed types, and that there are far more 



202 Educational Psychology 

simply ordinary people than there are of all the ' types ' put 
together. I report, to illustrate this point, the substance of all 
that Stern says in favor of the multiple type theory in his five 
chapters on Sensitivity, Perception, Memory, Association and 
Apprehension ['oo, pp. 40-77]. 

On p. 43 f. he says, " We know the enormous gap which exists 
between the unmusical and the musician in the discrimination of 
pitch, between the perfumer and the ordinary person in the 
recognition of odors, between the painter and the book-worm 
in the delicacy of color perception." On the contrary, 
between the keenest of the non-musical and the dullest of 
musicians in the discrimination of pitch there is no enormous 
gap, but an enormous overlapping (see Spearman, '04 b, pp. 90 
and 92). Stern himself later points out that a little special prac- 
tice bridges the ' enormous gap.' 

Stern mentions (p. 46) " the types of the external observer 
(the experimental scientist, possibly) and of the introspective 
thinker (the mathematician or metaphysician, possibly)." But 
these are not distinct, contrasting types. The experimental 
scientist is far more likely to be a good mathematician than is the 
ordinary man. Mathematical ability and interest are in no sense 
confined to the metaphysicians. The good external observer may 
be excellent at introspection, and the man with a strong interest 
in his inner life of thought is much more likely than the average 
man to have a strong interest in external facts. 

Stern's next group of types are the 'Anschauungstypen.' In- 
dividuals of the visual type, for instance, " imagine and dream 
in the most vivid visual images ; they notice and retain colors, 
forms, faces with especial ease ; they reproduce what is spoken 
predominantly with the aid of images of the printed words ; in 
fact they in general construct their world of ideas in great meas- 
ure out of visual elements." The more such extreme develop- 
ment of any one sense-sphere exists in a man, the more " the 
others are restricted to their necessary, indispensable and irre- 
placable functions." (p. 48) But here again the facts are in 
opposition. Such cases as Stern describes are extreme and very 
rare divergences from common mediocrity, not centers near which 
most men are located. 

Stern further divides men into a ' formal ' and a ' material ' or 
* content ' type in their ' Anschauung ' or mental dealings with 



Individual Differences in Combinations of Traits 203 

concrete objects. The formal type gets the rhythm of a piece of 
music easily, but the melody only with difficulty. The * content ' 
type gets the melody well, but the rhythm badly. "The former 
type notices and retains above all the temporal grouping of the 
sounds, whose qualitative nature and relations stay far in the 
background. With the latter type, on the contrary, it is just the 
material of the sensations, the succession of different pitches, 
which is made the instrument of musical perception." (p. 55) 
But no evidence is offered of this supposed inverse correlation, 
and all that is known of the relation leads to the expectation that 
it is positive, the individual best at getting rhythm being better 
than the average at getting melody also. 

Stern supposes these contrasting types to exist for spatial facts 
also. Ability with position and outline denotes one type ; anility 
with color, light and shade, another type (p. 57). But here 
again the supposed inverse relation is really direct The supposed 
types are two extreme and rare divergences from the real single 
type, an individual who is mediocrely gifted with both the ' form ' 
and the ' material ', with both line and color. 

In the case of memory. Stern reports, not multiple types, but 
gradations from single types, with the single exception that he 
quotes with modified approval, " Who learns easily, forgets eas- 
ily also ; who learns with difficulty, retains better." This is, again, 
contrary to the facts. 

Under types of apprehension or apperception. Is given the 
classification of individuals as describers, observers, emotional, 
and scholarly, made by Binet ['97] on the basis of their written 
descriptions of a single picture, and their classification as describ- 
ers, observers, imaginative and poetic, and scholarly, made (also 
by Binet) on the basis of written descriptions of a cigarette. 
Stern points out that much more elaborate examinations of the 
children are necessary. Leclere ['98] got, in a single experi- 
ment, seven types, which, also, are not at all distinct. Of course, 
many samples of each child's ' apprehensions ' or ' apperceptions ' 
of objects must be collected and classified independently by many 
competent psychologists, and the exact rating of each person on 
scales for scholarliness, imaginativeness, and so on must be given, 
before one can tell whether the individuals are grouped around 
one type or around several. The question is not whether Profes- 



204 Educational Psychology 

sor Binet can pick out certain papers that are distinctly different, 
but whether the common judgment of experts will rank the indi- 
viduals in classes that are distinctly different. 

The above is all that is given as evidence for the multiple type 
theory in the first 35 pages of Stern's inventory of types. The 
balance of his discussion, devoted to Types of Attentiveness, of 
Activity in Combining Facts, of Judgment, of Reaction, of Feel- 
ing, of the Tempo of Mental Life and of Mental Work, would 
give, if anything, less satisfactory evidence. The same lack would 
be found in the writings of Kraepelin, Binet, Meumann and their 
students. 

In general the case is stronger for the single type theory in 
combinations of original traits than in traits produced by train- 
ing. One form of training — one environment — may possibly pro- 
duce in every individual who is subjected to it certain large 
increases in certain mental traits and certain large decreases in 
others. All its subjects then tend thereby to differ much from 
all other men, and to be much alike among themselves, that is, to 
cluster around a type of their own. Such is not without reason 
supposed to be the case with residence in a given nation, frontier 
life, city versus country life, household industry versus factory 
industry, slavery versus freedom, and the like. Just as, in any 
one trait, the action of disproportionately large factors may cause 
multimodality, so, in any combination of traits, the action of dis- 
proportionately large factors may cause multitypality. And 
doubtless there would appear many minor eminences upon our 
relief-map of human nature due to the influence of ' nation lived 
in,' ' language spoken,' ' occupation followed,' and the like. The 
form of distribution of individuals in respect to combinations of 
traits, as in respect to single traits, is a secondary result of the 
nature and interrelations of the factors that produce the amounts 
of the traits. There is no mysterious force of mental life herding 
all individuals of the same sex, age and race around mediocrity. 
Nor is there such a force separating them out into clusters 
around distinct types. The former condition certainly occurs 
in the case of many combinations of traits. The latter may very 
well occur in the case of others. Knowledge of just what does 
occur demands objective measurements of each of many individ- 
uals in each of the traits in each of the combinations in question. 



Individual Differences in Combinations of Traits 205 

Individual Differences in the Average Amount of a 
Combination of Traits 

There are many combinations of traits which can be reduced to 
single traits by abstraction from some of their particulars. Sup- 
pose, for example, that A and B are measured in respect to 
efificiency in marking A's, in marking words containing each the 
two letters a and t, in marking hexagons on a sheet of various 
simple geometrical forms, in marking grays of a certain intensity 
on a sheet with 200 squares of grays of five intensities, and in 
marking misspelled words on a sheet containing a passage with 
100 out of 500 words misspelled. Suppose the results to be, in 
terms of the variability for each trait : — 

A B 

Marking A's -i.i +1.0 

a-t words -1.4 +7. 

" hexagons -.6 +1.2 

" grays .0 -.2 

" misspelled words -1.7 +1.4 

B-A equals 2.1, 2.1, 1.8, -.2 and 3.1 respectively. 

If we abstract from the particular differences and ask only 
concerning the condition of A and B, and their difference, in 
average efficiency in marking these Hve sorts of visual objects, 
the result is that A= -.96 (-4.8 divided by 5), B=+.82 
(+4.1 divided by 5) and B- A= 1.78. 

Such abstraction from certain particulars of each of a combi- 
nation of traits can be, and is, in both ordinary and scientific 
thinking, carried so far as to unite in a single trait very diverse 
features of intellect and character. From the combination of all 
the accuracies of discrimination with this and that length, color, 
weight and the like, may be got the one trait, accuracy in sensory 
discrimination. From the quickness of formation of each of a 
thousand habits, is derived the single trait, rate of learning. Ac- 
curacy, quickness, efficiency, permanence, amount of improve- 
ment, rate of improvement, and acceleration or retardation in the 
rate of improvement, are important cases of the measurement on 
one scale of some feature of an individual's condition in a group 
of traits. Originality, courage, timidity, suggestibility, scholar- 
ship, judgment, interest and curiosity are samples from a long 
list that could be made of terms, each used with comparatives to 



2o6 Educational Psychology 

denote, though very crudely, a man's position on a single scale. 
This position or amount would, however, be the resultant of many 
manifestations of what would have to be scored as a combination 
of many traits, if represented in full, concrete detail. 

For all such one-scale-representations of combinations of traits, 
the entire theory of single traits given in Chapter VIII holds good. 
In particular, the single type theory holds of them with fewer 
exceptions. For some one large cause will much less often act 
upon a man with the same effect in all the traits of a combination 
than in some one of them. So, whereas, in discrimination of the 
tastes of wines or teas or the like, men may be divided into an 
ordinary and an expert class, they will not be, in respect to ac- 
curacy of sensory discrimination in general. Similarly, though, 
in knowledge of the Latin language, men may fall into two groups, 
— an ignorant group and a group varying around some knowl- 
edge, — in knowledge of languages in general, they do not. 



CHAPTER XI 
Extreme Individual Differences : Exceptional Children 

From the discussion of the distribution of mental traits in 
Chapter VIII it is evident that, unless peculiar causative or select- 
ive agencies are at work, there will be a few individuals who will 
possess so little of any given capacity or quality as to be obviously 
' defectives ' in it, as well as a few who will possess so much 
as to be obviously * prodigies.' There will be a larger number 
who will possess so little as to merit the popular term ' weak ' 
in color vision, memory, self-control, moral sense, general intelli- 
gence or whatever the trait may be. These, again, will be balanced 
by an approximately equal number of ' remarkable ' or ' excep- 
tionally gifted.' 

If the mental trait in question is the compound of many traits 
which we call intelligence, we shall find at the lower end of the 
distribution curve children whom medical diagnosis would name 
idiots, and next them a number who would be termed imbeciles, 
and nearer still to the average the group to whom the name weak- 
or feeble-minded would be applied. If the mental trait is the 
compound called ' morality ', the individuals at the low extreme 
will perhaps be diagnosed as cases of ' moral insanity ' or as 
' moral degenerates.' If the trait be more specific, for instance 
if it be ability to learn to spell, ability to learn to read, cruelty, 
musical ability, memory, visualizing power or what not, we shall 
find few, if any, special names for different degrees of its posses- 
sion, though there will as truly be defectives in respect to any 
such specific mental trait as in respect to general intelligence. 

The means which educational endeavor will use and the re- 
sults which may be expected therefrom will, in the case of any in- 
dividual, depend upon his amount of the trait in question. No 
one, unless he were himself an ' idiot ' in the trait of common 
sense, would train a genius and an idiot alike or expect them to 
develop alike. At present there is a widespread practice of 

(207) 



2o8 Educational Psychology 

providing separate treatment at home or in institutions for idiots 
and imbeciles, though some are to be found in the common 
schools. And there is a growing demand for institutions and 
separate classes for the feeble-minded. Notable moral defectives 
are being cared for in separate classes in some cities. They also, 
when the parents are wealthy, find refuge in private schools of a 
certain type and in the somewhat mercenary ministrations of 
private tutors. The children exceptional in their great superiority 
to the average are not systematically given any special attention 
except here and there by systems of rapid promotion. 

For the proper treatment of exceptional children we need 
knowledge of the exact distribution of all the mental traits which 
we desire to develop or abolish, of the causes which determine 
an individual's station in each, of the symptoms by which we may 
conveniently find out any one's station in each, and of the agencies, 
educational, hygienic and medicinal, which alleviate or in- 
tensify the different conditions. The last involves the study of 
the differential action of stimuli upon individuals of different 
stations. For instance, the training of idiots should rest upon : — 

1. A consideration of the distribution of intelligence which 
will tell us what the frequencies of different degrees of low mental 
capacity are. 

2. A study of the extent to which original nature decides an 
individual's station in intelligence, and of the displacements of 
individuals from their original station to a lower station by acci- 
dent, disease, unwise training, and the like. 

3. A study of the physical and mental symptoms which enable 
us to measure a person as very, very low in intelligence. 

4. A study of the influences of climate, food, operative sur- 
gery, medicines, manual work, school work, good and bad ex- 
ample, etc., which make the mental condition better or worse. 

In the case of idiocy, imbecility and pronounced feebleness 
of mind, psychology, mental pathology and medicine could show 
a respectable array of facts for the student, though precise quan- 
titative studies fit to serve as models for study are very rare. We 
know, at least roughly, the frequency of intellects so defective as 
to disturb the home, resist school influence and excite popular 
pity or derision (about i in 500). We know that, in all prob- 
ability, by original nature human beings are distributed approxi- 
mately according to the ' probability ' distribution, with some 



Extreme Individual Differences 209 

elimination at the low end, and that selection from the germs 
produced by one's ancestry decides one's position ; that the ordi- 
nary circumstances of life in which people differ do not much 
alter one's position compared with his fellows, but that many 
special influences, e.g., brain injuries, hydrocephalus, cretinism, 
scarlet fever, and the like, may displace a person to a lower sta- 
tion. Some of these influences probably act indifferently upon 
individuals of all original stations, so that, so far as concerns 
them, idiocy may be caused in one of the most intelligent ancestry. 
On the other hand, many of them produce idiocy only upon the 
fertile soil of originally weak mental structure. As regards 
symptoms, we are not so well off as we may hope to be in the 
future. Idiocy can not be recognized as early in life as it should 
be. Nor can it always be distinguished from mere backward- 
ness ; nor can its different degrees be measured with convenience 
or with precision. As regards treatment for amelioration, we 
have a great amount of information, though not all of the best 
quality. 

But if we look for similar information concerning other men- 
tal defects we are doomed to disappointment. And exceptional 
children at the high end of the distribution curve have been so 
little studied that the very words, exceptional and abnormal, are 
commonly used to refer only to those exceptionally defective. A 
systematic treatment of the whole subject is thus out of the ques- 
tion and we must be content with (i) a series of rather discon- 
nected and ill-proportioned comments representing the present 
state of knowledge and opinion on matters which concern edu- 
cational theory and practice and (2) an outline which will sug- 
gest what we ought to know but do not. 

Exceptional Supe:riority 

It is a corollary from the facts of the last three chapters that 
exceptional superiority exists in the case of any mental trait or 
combination of traits, and that the greater the degree of superior- 
ity, the more exceptional it is. Some of the obvious and practi- 
cally important cases are: — total intelligence, mental balance, 
efficiency or capability, energy, quickness of mental processes, 
breadth of mental processes, strength or intensity of mental pro- 
cesses, abstract power, permanence of memories, mathematical 

14 



210 Educational Psychology 

ability, musical ability, ability in drawing or painting, mechanical 
insight, steadiness, courage, sociability, affection and enthusiasm. 
The list might of course be indefinitely prolonged. 

The cause of exceptional superiority is original nature plus 
or minus a displacement, commonly slight, due to environmental 
influence. The environment may displace a person downward to 
a great extent, but upward much less easily. The forceps of 
the physician, the strain of disease, the shock of brain concussion, 
may reduce original superiority to pronounced defect ; but medi- 
cine, favorable training and the impetus of zeal seldom elevate 
a mediocre person to top rank. In the case of the combination of 
gifts which we call intelligence they never do ; for it is only by 
the concentration of much energy in a narrow line that an orig- 
inally inferior person becomes superior. For him to do so in 
all lines is impossible. 

The symptoms of superiority in any trait are clear when the 
trait itself can be directly measured. It is easy to tell an excep- 
tionally good speller in school, or scientist in adult years, or sol- 
dier in war, or orator in the pulpit. But when we have to infer 
the future from present and past symptoms in young children, 
or judge a general trait from a few particular manifestations, 
our inferences lack surety and precision. Superior efficiency in 
life's work, for instance, is not at all clearly shown by superiority 
in school tasks ; success in formal grammar is not clearly symp- 
tomatic of general abstract ability ; the best boy in a thousand in 
discriminating length may not turn out much, if at all, above 
the average in general keenness of sense discrimination. When 
the relationships of a great many mental traits have been worked 
out in the way shown in Chapter IX, any one measurement will 
serve as a symptom to an extent now impossible. At present 
a wise rule is never to infer from a symptom any condition 
which moderate effort will enable you to measure directly, and 
never to infer future conditions from present symptoms with- 
out continuing observations into the future and modifying your 
inference as they direct. 

The development in individuals of a trait in which they are 
exceptionally superior would undoubtedly be aided by training 
different from that of those who approach the modal condition, 
but experimental studies must be made before any safe decision 
can be reached as to what sort that training should be. 



Extreme Individual DilTerences 211 

Exceptional Inferiority 

The distribution of mental traits at the low end has not been 
determined ; for the children accessible to the scientist in schools 
probably do not include all of the children defective in any im- 
portant particular. Most of those who are very deficient in 
general intelligence are sure to be secluded at home or in institu- 
tions. Some of the moral defectives will be in reform schools, 
or will be habitual truants or the companions of thieves and 
tramps, or will be in the care of private schools or tutors. To a 
less extent those very deficient in memory or abstract power or 
nervous control will tend to disappear for a longer or shorter 
time from the schools. It is probable that the distribution in many 
cases would deviate somewhat from the normal, taking a form 
like Fig. 30 (p. 153). The increase of defectives over the prob- 
able frequency would be due to the action of environmental 
forces which may lower a person from almost any station but do 
not raise him far. For instance, there seem to be many more 
people totally blind than just able to see, the passage from good 
eyesight to blindness being more frequent than the opposite. 

Exceptional inferiority characterizes some members of the 
human species in almost every mental trait or combination of 
traits. The list given on page 2ogi. is appropriate here. Atten- 
tion may also be called to defects of the senses ; defects of atten- 
tion ; defects of nervous action, e.g., chorea; to the cases where 
a very great amount of a trait is a defect, e.g., cruelty or the 
instinct to possess oneself of what one desires ; the minor automa- 
tisms, such as biting the nails or counting groups of objects ; 
morbid or useless impulses, such as touching every tree one 
passes ; and fetichisms, e.g., great afifection for a red rag. 

The causes of exceptional defects are the same as of excep- 
tional superiority, but, as has just been said, environmental causes 
play here a more important role. Their action has been carefully 
studied only in the case of defects of sight, hearing and general in- 
telligence, nervousness, choreic disturbance, and the psychological 
defects with which medical practice deals. To the medical liter- 
ature on these topics the reader is referred with the warning that 
precise quantitative statements will, unfortunately, rarely be given. 

What was said about symptoms in the case of exceptional su- 
periorities may be applied equally here. In the case of general 



212 Educational Psychology 

lack of intelligence there will be some special facts to be noted. 
Such additional iiiformation is also at hand in the case of those 
other defects which have received the attention of medical science. 
The reader is referred to text-books on sense defects, on children's 
diseases and on idiocy and imbecility. 

We know almost nothing about the remedial action of special 
forms of training upon those mental defects which medical prac- 
tice has disregarded. Leaving to one side such means as should 
be prescribed and administered by a physician, we may make 
the following recommendations : — 

For nervousness : outdoor life, much absolute rest, free- 
dom from competitive work and the exciting features of school 
and social life, but not from participation in both physical and 
mental work. 

: For hysteria : outdoor life, removal from the home environ- 
ment, calm but insistent training in good habits, the example of a 
well-balanced, unemotional teacher, objective interests in nature, 
industry and human affairs, freedom from the exciting features of 
school and social life. 

For general intellectual weakness : removal to a special insti- 
tution, a stimulating physical and mental environment (though 
not for the few cases complicated with great nervous irritability), 
stirring physical play, outdoor life, systematic stimulation of 
the senses and of curiosity, the arousal and direction of bodily 
movements, systematic physical training. 

The teacher or the consulting psychologist needs the cooperation 
of the physician in almost all cases of mental defect. Their causes, 
symptoms and relief are all connected with physical changes. 
These are sometimes apparent to the ordinary practitioner, as in 
defective school work due to indigestion or nasal or throat obstruc- 
tions ; sometimes apparent to the specialist, as in defective ability to 
read and spell due to retinal defects ; sometimes unrecognizable, 
but yet doubtless existing, as in defective ability to form general 
and abstract notions. 

General Intellectual Defect 

The psychology of those deficient in general intellect (idiots, 
imbeciles and the feeble-minded) has been discussed at some 
length by many students. The chief questions concern classification, 
causation, symptoms and treatment. The aim of this section will 



Extreme Individual Differences 213 

not be to review the facts and opinions that have been stated, but 
simply to help the reader to study the literature of the subject 
intelligently. 

English writers agree in using the terms idiots, imbeciles and 
feeble-minded to refer in order to the three lowest conditions of 
intellect. This common use makes the terms very convenient, 
but it is certain from our knowledge of the distribution of mental 
traits that any effort to separate sharply idiocy from imbecility, 
and the latter from feebleness of mind, must fail. The words are 
but names used roughly for sections of a continuous surface of 
frequency. The obvious thing to do is to arrange a scale for 
intellect and describe that of each individual by his precise station 
on that scale, not by a vague name. 

Numerous more detailed classifications have been proposed, some 
on the basis of mental traits, e.g., the degree of capability in 
attention, the capacity for feeling relationships, the efficiency of 
the senses and motor apparatus ; some on the basis of the conditions 
accompanying them, e.g., a classification into paralytic idiocy, 
epileptic idiocy, syphilitic idiocy, etc. ; some on the basis of causa- 
tion, e.g., a classification into congenital and acquired. 

The fact is that the varieties of human nature referred to by 
the words idiot, imbecile and feeble-minded, are numerous, that all 
sorts of combinations of mental qualities, accompanying diseases, 
causes and physical stigmata occur, and that no simple classifica- 
tion can be adequate for all purposes. To grade idiots before 
courts of law or for treatment in an asylum, a classification by 
mental ability as measured by attentiveness or some other mental 
traits may be best ; to provide for medical treatment their separa- 
tion into groups according to concomitant diseased conditions may 
be wise ; for medical science the pathological changes in the brain 
correlated with the mental conditions may be the key to the useful 
classification ; and so on through possible classifications for 
prophecy of amelioration, for educational treatment, and for 
psychological analysis. 

I suggest as one of the most fundamental and useful classifica- 
tions a division into : — ( i ) Those whose condition is due to original 
nature, who hold the position in the scale of intelligence which 
the make-up of their germs decreed, and (2) those who by accident 
or disease have been displaced downward from their original 
positions in the distribution scheme. The condition of members 



214 Educational Psychology 

of the first class should, as knowledge advances, be capable of 
early diagnosis ; they should possess many characteristics in com- 
mon and allow of further subclassification ; medical treatment 
would be relatively inefficient, but from wise educational and 
hygienic control we should expect much. The second class would 
present fewer characteristics in common ; strictly medical or 
surgical treatment would be of more importance than educational 
training ; they should be studied in connection with mental diseases 
in general. Roughly it would be fair to say that for the first class 
we need psychologists and special schools, while for the second 
we need physicians and hospitals. 

It seems desirable further to separate children who are feeble- 
minded, and are destined to remain so, from those who are simply 
backward in mental growth and may eventually reach a fair 
station. We know that in physical growth some children who 
from six to twelve or thereabouts are far below average stature 
for their age, in later years make up part or all of the deficiency, 
and there are many reasons for believing the same to be the case 
with mental growth. The essentially dull should never be con- 
fused in theory or in actual treatment with those temporarily 
deficient. 

To the discussions of the causation of idiocy, imbecility and 
feebleness of mind in the standard texts I have nothing to add 
save that where so complex and so interrelated causes are studied, 
great help will come from more precise measurements of amount 
and from estimating the efficiency of partial causes by the coeffi- 
cients of correlation between them and their supposed effects. 

In the case of the symptoms of these conditions also, precise 
measurements with objective tests would permit an advance in 
knowledge which is impossible so long as cases are studied by an 
undefined general examination and described by the loosest of 
adjectives. 

Amongst the recommendations for educational treatment those 
which are in accord with the following facts should be given 
especial weight : ( i ) Learning by the unconscious selection of 
reactions which produce pleasure and the elimination of reactions 
which produce pain, is widespread throughout the animal 
kingdom and may be depended upon when learning from explana- 
tion, insight and general principles is impossible. (2) The lower 
the mental capacity of an individual, the closer in time must the 



Extreme Individual Differences 215 

pain or pleasure follow the reaction. (3) The connections between 
impressions and obvious movements of the body are more easily 
formed than between impressions and ideas or the more subtle 
movements of the muscles of the face, throat and trunk which 
perhaps always parallel ideas. The first type of connections may 
be formed in individuals incapable of the second. The so-called 
kindergarten and manual-training methods are therefore particu- 
larly suited to defectives. (4) Mental defect often involves a 
sluggishness of action on the part of the nervous system which 
makes a rapid succession of stimuli interfere with each other and 
result in mental confusion, and necessitates the continuation of the 
same stimulus over a long interval or its repetition. (5) The 
extreme narrowness of the field of attention and the inability to 
control sudden alternations of attention from one topic to another 
and back make it necessary for the teacher to take up but one small 
issue at a time, to progress along one single line. (6) Knowledge 
of relations, including appreciation of general and abstract 
notions and the symbols for them, is practically beyond the 
capacity of these inferior minds. It is therefore wisdom not to 
pretend to give it and economy not to try. They need sense 
training, object-lessons and concrete work throughout. (7) Sug- 
gestion is potent here as elsewhere. By treating the feeble-minded 
like normal children as far as is possible we help to make them 
more normal. They should have their school, church, entertain- 
ments, trades, excursions and the like. They should not be made 
to appear peculiar in dress or encouraged in eccentric habits. 

Exact Measurements of General Intellectual Defect 

Measurements of various mental traits in intellectually deficient 
children and adults have been made by Galton and Jacobs ['87], 
Johnson ['95], Wylie ['00], Kelly ['03], Lobsien ['03], Kuhl- 
mann ['04], Norsworthy ['06], Binet and Simon ['09], and 
others. The main purpose of these measurements has been to 
describe the defect more exactly and to analyze it into its factors. 
Norsworthy attempted also to measure the effect of a year's 
growth and institutional training. 

Whatever intellectual function is tested, its efficiency is found 
less than in the average man. The idiots, imbeciles and feeble- 
minded are inferior in sense-discrimination, memory, the rapidity 
and accuracy of sensori-motor habits, quickness of association, 



2i6 Educational Psychology 

span of attention and other traits. This was to be expected. But 
they are not equally inferior in all functions. And it is the main 
service of psychological tests to measure their relative inferiority 
in different traits and so verify, refute or modify existing notions 
as to the factors involved in idiocy, imbecility and feebleness of 
mind. 

The question of whether a child is more inferior in one trait, 
say, memory of a list of simple words, than in another, say, ability 
to select from ten dominoes the one like a sample shown, is some- 
what subtle and cannot be answered by simply measuring his 
abilities in the two cases. Suppose that, of ten words spoken once, 
he remembers 5, and that in selecting a domino (the ten with the 
fewest spots being used) he takes nine seconds, making no errors. 
From these records alone we do not know whether he is inferior. 
But even if it is known that the average person of his sex and 
age remembers 7 such words in such a case and matches the 
domino in 5 seconds, the question of the defective child's relative 
inferiority in the two traits is still unanswered. Two words less 
than seven and four seconds more than five are not commensurate. 

They may be made commensurate by expressing each as a 
multiple of the variability of men in general for the trait in ques- 
tion. Thus if the median deviation of men in general from the 
average of 7 words remembered is 1.2 words, the defective's 
mferiority in memory is i§ times the median deviation in memory. 
If the median deviation of men in general from the average 
(5 seconds) in matching the domino is i second, the defective's 
inferiority in matching dominoes is 4 times the median deviation. 
In so far as the variability of men in general may be taken as the 
standard by which inferiority is to be measured, he is 4/1.67, 
or 2.4, times as inferior in the matching test as he is in memory. 

Now the variability of men in general, though far from equal 
in all traits, is a very useful standard for the present purpose. 
The ratio of the defective's deviation from the central tendency of 
his age and sex to that found in general is just what one needs 
to know. ' Worse than all save 10 per cent in weight,' ' worse 
than all save 10 per cent in height,' ' worse than all save 10 per cent 
in memory,' ' worse than all save 10 per cent in attentiveness ' — 
may very usefully be treated as ' equally inferior in weight, height, 
memory and attentiveness.' If a defective is in height as far below 
the central tendency as the 25 percentile (the median of all those 



Extreme Individual Differences 



217 



men who are below the central tendency), in weight twice as far 
below, in memory three times as far below, and in attentiveness five 
times as far below, he may usefully be said to be five times as 
inferior in attentiveness as in height, one and a half times as 
inferior in memory as in weight, and so on. 

Thus in Table 21 (arranged from data given by Norsworthy 
['06, pp. 54-67]) the measures are all in terms of the median 
deviation of the age and sex in question for the trait in question. 
Each row gives the measures in the case of one individual. Each 
column gives the measures in one trait. Each entry reads : 
'Individual .... is .... times as far below* the central tendency 
of American children in general of his age and sex as is the 25th 
child from the bottom out of 100 children.' 



TABLE 21. 

Samples op Measurements op the Feeblb-Minded, Made Commensurate 
One with Another by Being Transpormed Each into Multiples 
OP THE Median Deviation op the Trait in Question 
por the Age and Sex in Question. 

Marking 
A's and 

Discrim- words Mem- Mem- Controlled association, 

ination contain- ory of ory of 

of ing a lists of sen- Part Genus Opposites. 

weight, and t. words, tences. whole, species. I. II. 

A. — .11 —1.94 —6.73 —3-42 X X X X 

B. — 2.51 — 2.93 — 4.17 — 350 — 11.00 — 6.60 — 5.00 — 8.40 
Q. X X X -5-00 X X X —3-82 
D. —3-54 — 133 —2-49 —5-41 X —1300 —4.80 —6.00 
E —4.01 —2.73 —8.57—13.00 —5.65 —8.75 

F X X X X X X 

G. — 1. 71 — 3.69 — 4. II — 3.33 — 10.00 — 16.60 — 5.65 — 8.15 

H. +1.11 —409 —5.36 -3-39 t X —4-87 

I. —6.54 —4.42 —5-98 —3-75 X X X 

J —2.23 —5-30 X X t X 



A group of defectives thus rated in commensurate units may 
then be easily compared, with respect to their inferiority in diflPer- 
ent traits, by a modification of the method used for comparing the 
sexes and races. The modification necessary is to use in place of 
'per cent of defectives equalling or exceeding the median ability 

*Except for individual H in discrimination of weight. 

JSignifies that the individual failed entirely in the test in question. 



2i8 Educational Psychology 

of people in general of that age and sex ' the ' per cent equalling or 
exceeding some lower degree of ability ' of people in general, such 
as the 25 percentile (or median of the half below the central 
tendency) or the 12^ percentile (median of the lowest quarter of 
people in general of the given age and sex. For instance, if: — 
In height 61 per cent of defectives are above the 25 percentile, 
In discrimination of weight 28 per cent of defectives are above the 

25 percentile. 
In memory of sentences 10 per cent of defectives are above the 

25 percentile, 
In giving opposites of words i per cent of defectives are above the 

25 percentile, 
it is clear that the inferiority is greater in giving opposites than 
in memory of sentences, and so on. 

Of the investigators of the psychology of the intellectually 
deficient Norsworthy is the only one who has put the results in 
such a form as to measure relative inferiority. Of the others some 
have not even measured the variability of the defectives or of 
people in general in the trait in question, so that only a very rough 
estimate of relative inferiority can be got from their figures. 

From the best estimates that I am able to make, the order of 
inferiority of intellectual traits* in defectives confined in institu- 
tions seems to be : — Sensitivity, in which, on the whole, 25 per cent 
are above -i P. E. Speed and precision of sensori-motor connec- 
tions, in which on the whole 20 per cent are above -i P. E. Speed 
and precision of connections between idea and idea or between idea 
and act, in which, on the whole, i to 10 per cent are above -i P. E. 
Speed and precision of selective associations or of responses to 
parts or elements of situations, in which, on the whole, o per cent 
reach -i P. E. 

The experimental data do not give a very clear picture and 
universally true analysis of the condition which relegates 
individuals to the class idiots, imbeciles and feeble-minded. But 
they do show that such a clear picture and uniformly true 
analysis is not to be expected, and that individuals thus classified 
vary greatly among themselves in the nature of their defects. They 
also show negatively that no single defect is an adequate explana- 
tion of their condition. Seguin's notion that weakness in sensitiv- 
ity and responsiveness is the cause of idiocy was certainly far from 

*In height and weight about 60 per cent are above -i P. E. 



Extreme Individual DiiTerences 219 

true. On the contrary, power of connection is relatively much 
weaker than power of reception or of action. Sollier's notion that 
instability of thought, — lack of power to control attention, — is the 
cause is also certainly wrong; for it leaves unexplained the 
enormous slowness in their mental operations, including responses 
to situations like the sight of food or the thought of candy, to 
which attention is easily given. It also leaves unexplained their 
relatively greater inferiority in all connections involving ideas than 
in mere sensori-motor connections, like sorting colored beads or 
marking a familiar letter. 

If one is to hazard a description of a group which varies 
enormously within itself, he may say of these exceptionally unin- 
tellectual children : They are weak in the number, delicacy, 
complexity, speed of formation, and permanence of associations of 
whatever sort ; especially so when one or both of the members to 
be connected is an idea. They are weaker in the analysis or 
abstraction of elements out of gross total situations, and the deter- 
mination of thought by the action of a part or element or aspect 
of a situation. They are as a result weakest in those functions 
which require the cooperation of many selected associations and 
the partial activity of many relics of past experiences in the service 
of some complex and ideal situation or problem. They are also 
usually very weak in the instinct of mental activity, in the 
satisfaction with mental life for its own sake. They represent the 
extremes of the condition found in stupid people generally, the 
opposite of the gifted person who connects rapidly, precisely and 
permanently, analyzes facts into their elements easily and often, 
thinks facts together, is guided by remote and ideal ends, and 
enjoys thinking for its own sake. 

They are inferior in sensitivity, but their appearance of being 
very much so is due in part to their willingness to live in mental 
torpor, their failure to connect the sense impressions with any- 
thing further, and their more frequent failure to analyze out color, 
size, shape, and the like from the gross total situations whose 
partial aspects they are. They are inferior in movement, but 
their appearance of very great inferiority in it is due in part to 
their failure to connect movements with percepts and ideas or to 
analyze out and get control over portions of movement-series and 
recombine them anew. They are very inferior in attentiveness 
from the point of view of one to whom attentiveness means power 



220 Educational Psychology 

of attention to elements rather than to gross totals, intellectually 
fruitful things rather than the natural objects of the instincts 
connected with food, fears, sex, and the like, or past and future 
situations rather than present situations. But the words ' lack of 
power of attention ' do not properly explain but only name this 
fact. The facts given above are again the real explanation. 

To this characterization there are numerous exceptions. 
Sensory or motor defects (especially speech), if not overcome by 
proper education, may simulate general intellectual defect. In 
special lines a feeble-minded child may manifest a fair degree of 
power of connection, analysis and even of selection. Learning 
may be (though it usually is not) very slow but very permanent. 
And so on with many other divergences. The experimental data 
show abundantly that the idiots, imbeciles and feeble-minded are 
subject to all the complexities of interrelations of mental traits 
described in Chapter IX. They are not to be thought of apart 
from the human species as a whole, but as certain very divergent 
members of it, by no means alike save in great inferiority in the 
complex of traits which we call intellect. 

There is an ill-defined group of children separated roughly from 
others of their age by the fact that they do not get on in school 
work and still are capable enough in many matters to make unjusti- 
fiable the title idiot, imbecile or feeble-minded, as commonly used. 
Theoretically this group is composed of a number of different 
species of individuals. Some fail in school work because of defects 
of vision or hearing which their teachers fail to allow for. Some 
are nervous, fretful and easily distracted. Some are extremely 
unimpressionable and slow. Some lack only the capacity to deal 
with abstract ideas and symbols and succeed well enough in con- 
crete acquisition. Some may possibly possess full capacity and 
lack only interest. Some are weak in intellect throughout, belonging 
on the border line between the brighter of the feeble-minded and 
the duller of the so-called normal children. Some are simply too 
immature for the work. Practically the group possesses the unity 
of a negative characteristic, inability to profit by the usual methods 
of teaching the usual subjects. In any school of a thousand pupils 
the principal can pick out from twenty to forty such children, who 
are the despair of their teachers, a hindrance to their classmates, 
and a source of worry to their parents. Even after sense defects 
are corrected or allowed for, after adenoids have been removed, 



Extreme Individual Differences 221 

even when wise teaching prevents excitement and nervous worry 
and arouses interest, a majority of these will be just as they were 
before. The group thus left has not, until recently, attracted the 
attention of medical science or of educational psychology to the 
extent that its practical importance deserves. 

Norsworthy ['06] gives data for the comparison of such a group 
of 30 girls, 8-13 years old, picked out from about a thousand in a 
city school on the ground of inability to profit by the regular 
school work, with ordinary children of the same age who lived in 
the same environment, attended the same school and were 
measured by identical tests given by the same individual. In 
giving instructions explanations were made very clearly and the 
process required was also shown by samples put upon the board. 
The measurements taken were as follows: 

1. Height. 

2. Weight. 

3. Body temperature (taken at the mouth). 

4. Pulse. 

5. Rate of movement; tested, (a) by the number of crosses made in ten 
seconds (two trials); (6) by the number of up-and-down movements made 
in ten seconds (two trials). 

6. Accuracy of movement; tested, (a) by the number of touches made 
in drawing a line between the lines of a maze; {b) by the regularity and 
evenness of the figures made in the tests for the rate of movement. 

7. Efficiency of perception (rate and accuracy combined) ; tested by 
the A test. 

8. Efficiency of perception (rate and accuracy combined) ; tested by the 
a-t test. 

9. Delicacy of discrimination of length; tested by the variable error in 
drawing a line equal to a lo-cm. line (ten trials). 

ID. Efficiency in a test of perception and movement combined, viz., the 
time taken to insert variously shaped blocks into a board made with depres- 
sions to fit them. 

11. Memory of unrelated words; number remembered out of ten after 
a single hearing (two trials) — red, dog, day, tree, buy, never, sick, song, 
boy, box, long, green, arm, inch, true, run, dress, break, friend. 

12. Memory of related words; number remembered out of ten after a 
single hearing (two trials) — school, teacher, book, desk, pen, read, write, add, 
spell, word, river, water, broke, flow, ice, cold, winter, snow, sled, skate. 

13. Semi-logical memory; memory of four simple dictations, viz., (i) 
I have one head, two eyes, two hands and ten fingers. (2) I sit in my seat. 
I read from a book. I write with a pencil. (3) One and two are three. 
Three and four are seven. Five and six are more than ten. (4) In the 
morning I go to school. After school I play. At night I go to bed. 

14. Ability in the formation of abstract notions, the appreciation of 



222 



Educational Psychology 



relationships and the control of associations; measured by the following 
tests: (A) to write the opposites of a given Hst of words; (S) to mark those 
words in a list which are names of things; (C) to write a word representing 
some kind of the thing named by a given word; (£>) to write a word repre- 
senting some thing of which the thing named by the given word is a part; 
(E) to write the opposites of a list of words, the converse of the list used in 
A, after the correct responses for A have been read to the class. 

The detailed results of the comparison can not be given here. 
Their general outcome is perfectly clear. In the physical traits 
there is very little difference except in the rise of temperature at 
the mouth in the course of twenty minutes of work at the tests. 
This invariably occurred with ordinary children, but in only 60 
per cent of the special cases. The pulse rate of the special cases 



6 -4-3-2-1012346 




-8 -7 -6 -5 -4 -3 -2, 

Fig. 70. The relative frequencies of difTerent degrees of ability in respect 
to trait 14 above, in the case of 73 mediocre nine-year-old girls (upper 
diagram) and 19 girls from eight and a half to thirteen years old, m a 
'special class' in a public school (lower diagram). The units of the scale 
are multiples of the median deviation of nine-year-olds. 



is a trifle lower. The difference increases as we pass from physical 
traits to tests of movement, then to tests of verbal memory and 
then to tests of perception, but even in the last case the special 
cases rank about with the lower half of ordinary children. But 
with tests 12, 13 and 14 the difference becomes increasingly greater, 
until in the last the special cases come to rank as the extreme end 
of the school population of their age (Fig. 70). 

The one chief and essential characteristic of these children is 



Extreme Individual Differences 223 

thus their inability to think in symbols, or with relationships, or in 
such a way as to let a number of processes combine to decide what 
a given thought or reaction shall be. Concrete facts they can think 
of and respond to one by one, but they can not think in symbols 
that stand for groups of facts or elements in facts. Nor can they 
think facts together in causal or other series, or respond correctly 
to related groups. In short they are the weakest members of a 
school population in thinking of the pure human type. Besides 
this main defect there is a diminution of mental vigor, quickness 
and tenacity along all lines. In no mental tests do they do as 
well, and they give us some reason to believe that as they grow 
older they will develop continually less and less rapidly than 
ordinary children and so fall farther and farther behind in the 
mechanical as well as rational capacities. 

Moral Defectives 

There are no general conclusions based upon exact measurements 
of moral deficiency and its causes and accompaniments. There is 
an abundance of ineffective detail stored up in medical comments 
upon so-called moral insanity and morbid impulses, in prison 
reports and in the minds of experienced schoolmasters. The 
greater complexity of the phenomena will always make the 
psychology of moral defectives more intricate than that of the 
feeble-minded. 

The one general truth which can be asserted is that all sorts of 
moral defects exist, are far from perfectly correlated, and are due 
to a multiplicity of causes. There are extremes of cruelty, deceit, 
egotism, passion, knavery, destructiveness and of all immoralities 
conceivable. There are boys and girls notably defective in only 
a single respect and others in whom every meanness and vice seems 
to thrive. We imagine, however, and probably with justice, that 
the correlations between certain defects are particularly high, 
so that certain combinations of traits are specially frequent. 

Such are perhaps features of moral defect characterized by : 
(i) Brutishness, extreme predominance of the animal instincts, 
shown, for instance, by brutality and teasing, excessive sexual 
appetites, fits of rage and sulking, unreasoning greed and 
malice; (2) extreme egotism and lack of appreciation of 
the feelings and rights of others; (3) extreme weakness 
of control and moral instability, shown by susceptibility to 



224 Educational Psychology 

all temptations and petty vices, alternations of affection with 
cruelty, anger with tears, peevishness, untrustworthiness, — an 
hysterical and irresponsible mental type, bad more because 
of the weakness of good habits than because of the 
strength of evil impulses ; (4) the existence of one or more 
morbid impulses of an immoral sort. Children may have intense 
desires to cut or tear, without being generally extremely cruel ; to 
run away from home and live a tramp life, without being generally 
extremely disobedient ; to be kleptomaniacs but generally fairly 
honest ; to be incendiaries without general destructiveness ; or to 
be sexually disordered without being of excessive passions. 

Of course there is no rigid adherence to these types. Combi- 
nations, intermediate conditions and children falling outside these 
groups all exist. The extent to which such a grouping of cases 
is allowable or useful can be told only after measurements of the 
correlations between special immoral traits have been made. 

Brutishness would seem likely to be due to original nature 
accentuated or relieved by training ; egotism would seem to be an 
original defect in sympathy coupled with lack of abstract intellec- 
tual power and commonly made worse by the spoiling and selfish- 
ness of parents ; moral instability seems to be due to original 
nervous instability displayed in moral more than intellectual 
matters as a consequence of feeble and vacillating parental inter- 
ference. The morbid impulses of a special sort are probably more 
ingrained in original nature and less influenced by environmental 
conditions. 

General moral defect commonly involves intellectual inferiority. 
Woods ['06] and Pearson ['07] find the correlation between 
intellect and character to be about .5. The brightness and 
precocity that seem to characterize many cases of egotism and 
moral instability are really glibness, pertness and lack of restraint. 
It is therefore likely that general moral defect is due in part to 
generally inferior nervous organization. 

Exceptional Rates of Grozvth 

Precocity, retarded development* and arrested development are 
terms loosely used to refer to children who are exceptional in the 

* The term retarded development is at times used not for an undefined 
slowness of growth, but for a slowness in growth which will later be made 
up. I shall therefore replace the two uses of the single term by the two 
terms sloiv growth and delayed groivth. 



Extreme Individual Differences 225 

rate of mental growth. As we find them in books they hardly 
mean anything more definite than very rapid growth, very slow 
growth, and absence of growth. But they may be made exact 
descriptive terms by the establishment of standards of change 
with age from which exceptional rates may be measured. 

By far the best arrangement would be to give stations above or 
below the average in rate of growth in just the same way as is 
done in the case of static conditions of a trait, and to speak in terms 
of these numerical stations rather than in the vague terms super- 
norm.al, normal, subnormal, and the like. If any individual's rate 
belongs to a distinct species of mental growth the fact can easily 
be made clear by giving the total distribution scheme as well as 
his station therein. 

As a matter of fact, precocity, retarded development, etc., are 
rarely measured thus directly from the rate of change. Instead, 
they are inferred from the fact that an individual is above or below 
the condition usual at his age. The term retarded development, 
for instance, is thus applied to a case which may be one of slow 
rate of growth at the time of observation, or of a slow rate in 
years long past, or of low initial station. This is unjustifiable. 
Exceptional degrees of ability should be dealt with apart from 
exceptional rates of change in ability. 

Precocity 

There is a popular opinion much encouraged by physicians that 
children who in early life grow mentally very rapidly and so 
attain high stations, are likely to come to grief, and be soon sur- 
passed in health and mental ability by their less precocious fellows. 
It is an illustration of the superficiality of human thinking that 
so unhesitating an acceptance should be given to the paradox that 
rapid mental improvement from birth to the age of ten should be 
an evil, but from twenty to forty the greatest of blessings. For, 
if we pass beyond a few striking examples which prove nothing, 
it is hard to see any evidence for the first statement of the paradox. 
On the contrary, bad physique and nervousness accompany dull- 
ness oftener than brightness ; and early mental superiority is 
prophetic of later. 

Men and women of eminent achievements in life are far more 
likely to be precocious in childhood than ordinary, dull or 
inefficient men are. Havelock Ellis ['04, p. 136 fif.] writes: — 

15 



226 Educational Psychology 

"The chief feature in the childhood of persons of eminent 
intellectual ability brought out by the present data is their 
precocity. This has indeed been emphasized by previous inquiries 
into the psychology of genius, but its prevalence is very clearly 
shown by the present investigation. It has certainly to be said that 
the definition of ' precocity ' requires a little more careful con- 
sideration than it sometimes receives at the hands of those who 
have inquired into it, and that when we have carefully defined 
what we mean by ' precocity ' it is its absence rather than its 
presence which ought to astonish us in men of genius. Judging 
from the data before us, there are at least three courses open to a 
child who is destined eventually to display pre-eminent intellectual 
ability. He may (i) show extraordinary aptitude for acquiring 
the ordinary subjects of school study; he may (2), on the other 
hand, show only average, and even much less than average, apti- 
tude for ordinary school studies, but be at the same time engrossed 
in following up his own preferred lines of study or thinking; he 
may, once more, (3) be marked in early life solely by physical 
energy, by his activity in games or mischief, or even by his 
brutality, the physical energy being sooner or later transformed 
into intellectual energy." ['04, pp. 136-137.] 

" Although we have to make allowance for ignorance in a large 
proportion of cases, and for neglect to mention the fact in many 
more cases, the national biographers note that 292 of 1030 eminent 
persons on our Hst may in one sense or another be termed preco- 
cious, and only 44 are mentioned as not precocious. Many of the 
latter belong to the second group, .... those who are already 
absorbed in their own lines of mental activity, — and are really just 
as ' precocious ' as the others ; thus Cardinal Wiseman as a boy 
was ' dull and stupid, always reading and thinking ' ; Byron 
showed no aptitude for school work, but was absorbed in romance, 
and Landor, though not regarded as precocious, was already pre- 
paring for his future literary career. In a small but interesting 
group of cases, which must be mentioned separately, the mental 
development is first retarded and then accelerated ; thus Chatterton 
up to the age of six and a half was, said his mother, * little better 
than an absolute fool,' then he fell in love with the illuminated 
capitals of an old folio, at seven was remarkable for brightness, 
and at ten was writing poems ; Goldsmith, again, was a stupid 
child, but before he could write legibly he was fond of poetry and 



Extreme Individual Differences 227 

rhyming, and a little later he was regarded as a clever boy ; while 
Fanny Burney did not know her letters at eight, but at ten was 
writing stories and poems." ['04, pp. 140-141.] 

" The very marked prevalence of an early bent towards those 
lines of achievement in which success is eventually to be won is 
indicated by the fact that in those fields in which such bent is 
most easily perceived it is most frequently found. It is marked 
among the musicians, and would doubtless be still more evident if 
it were not that our knowledge concerning British composers is 
very incomplete. It is specially notable in the case of artists. It 
is reported of not less than 40 out of 64 that in art they were ' pre- 
cocious ' ; only four are noted as not being specially precocious." 
['04, p. 142.]* 

In the case of 70 children chosen at random, for each of whom 
I had records of ability in the school work of grade 4 and of 
grade 7 or 8, that is at about the tenth and about the fourteenth 
and fifteenth years, I find the relationship between the abil- 
ity shown in the early and that shown in the later period to be 
not at all one of antagonism but of resemblance. The Pearson 
coefficients, uncorrected for attenuation, are : 

r for 4-7 grade (40 cases) =+.i8 

r for 4-8 grade (30 cases) =+.31 

If corrected for attenuation they would probably be about .3 and .5. 

The mistake current in educational literature seems to have 
arisen from a number of fallacies. First, physicians meet with 
cases of physical or mental breakdown in mentally superior chil- 
dren. They still oftener meet similar cases in mentally inferior 
children, but the former cases excite more pity and are more 
interesting and dramatic. They tend, therefore, to remain in the 
physician's mind while the others fade. Second, an interest in 
and acquaintance with topics suitable for older people, such as 
sex, theology or adult human social relations, is often taken to 
be the sign of a precocious mind. Now these phenomena are often 
morbid and may therefore well go with an unstable mental organi- 
zation and so be somewhat prophetic of disaster. But they are 
not per se indicative of superior mental growth. For the few 
supernormal children who exercise their gifts on such questions, 
there are many who are ahead in school, play, leadership and 
accomplishments. One should not take the word precocious in the 

*Loewenfeld ['03] corroborates the findings of Ellis. The same result 
has been obtained by other writers also. 



228 Educational Psychology 

bad sense of unbalanced superior gifts and argue from premises 
thus obtained to conclusions about precocity in the sense of gen- 
erally supernormal mental growth. In the third place, physicians 
often take the word of the parents for the children's precocity. It 
then means probably mere forwardness, ready talk, so-called 
' bright ' sayings and doings, and even impertinence. These all 
witness to inferiority disguised by lack of inhibition. The quiet 
child thinks of many much brighter things to say, but also has the 
strength of mind not to say them. Lack of inhibition and im- 
pertinence are prophetic of poor mental growth in the future be- 
cause they are indicative of it in the past and present as well. 
Finally it must be said that the average medical man in his ignor- 
ance of the subtle hereditary and environmental causes of mental 
breakdown grasps at any cause he can. If the child is dull, mental 
weakness is to blame ; if he is bright, precocity ! 

Slozv Growth 

In the absence of any quantitative studies of slowness of 
growth, this section will be limited to brief comments upon the 
question as to whether slowness of growth in one mental trait 
implies equal slowness in the growth of others, and the question 
of the desirability of a slow mental growth. 

Slowness of mental growth is undoubtedly specialized, though 
to just what extent is not known. An obvious illustration is 
given by the sex instincts, which may mature far in advance of 
or far behind the intellectual powers. So also with social facility 
or musical talents. The resemblances between traits in an indi- 
vidual in their rate of maturing are, however, probably much 
greater than in their final condition. 

Slowness of mental growth is in general an unfavorable sign. 
It is correlated slightly with low original capacity and low ulti- 
mate attainment. In some cases, of course, the growth is only 
delayed and the individual who seems to be far behind may come 
out well ahead. Moreover, as in height the boys who grow less 
than the average from twelve to fourteen grow more than the 
average from fourteen to sixteen, so in mental traits retardation 
before puberty may mean acceleration after it. 

The opposite view, a corollary to the superstition about pre- 
cocity, has gained credence, I fancy, first because of the supposed 
slowness of maturing of superior races, and secondly because of 



Extreme Indimdual Differences 229 

the supposed ill success at school of gifted men. But the ap- 
parent mental attainments of children of inferior races may be 
due to lack of inhibition and so witness precisely to a deficiency 
in mental growth. Moreover, we can not argue from inferior 
races to inferior members of one race. The failure at school work 
of children destined to become eminent men is a myth. The per- 
centage is far higher for thieves and paupers and lack-wits. 

Inefficiency due to slow mental growth, especially in those 
cases where the future will prove it to have been only delayed 
mental growth, must not, however, be confused with inefficiency 
due to inevitable incapacity. The correlation would have to be 
1. 00 to permit the interchange of these terms as synonyms. 

Accurate tests to differentiate inherent incapacity from im- 
maturity would seem to be of great practical value. They would 
prevent the injustice and discouragement due to mistaking the 
second for the first and the false hopes inspired by mistaking the 
first for the second. An approximation to such a differential 
diagnosis can be made by using the following tests : — 

A. Tests of Maturity Chiefly. 

Motor control (rate of tapping, rate of making crosses, maze tests). 
Memory of unrelated words, pictorial forms, etc. 
Perception {A test, a-t test, geometrical forms test). 
Delicacy of sense discrimination (of length and of weight). 

B. Tests of Intelligence Chiefly. 

Logical memory (memory of passages that involve connected and sys- 
tematic exposition or argument). 

Controlled association (alphabet and easy opposite tests or the like). 

Preception of relations (filling up the blanks in passages like the fol- 
lowing) : 

In everything that we do . . . need ... be both qilick . . . careful . . . 
we are . . . quick we do not get much done we care- 
ful we do not do our work . . . well . . . others. It is better to be careful 
. . . than to be quick . . . the best worker . . . the one . . . can do . . . 

things . . . do . . . well we can not all be the best, we can . . . 

improve. 

Let US suppose a boy who does not get on well in school to be 
tested and given stations in A and B with reference to the median 
for his age and sex. The lower his station is in A and the higher 
it is in B, the more chance there is that he will grow out of his 
difficulty. Conversely, the higher his station is in A and the 
lower it is in B, the greater is the probability that he is essentially 
dull. 



230 Educational Psychology 

Arrested Development 

The • phrase ' arrested development ' is used in medicine to 
mean just what it says. Bodily organs, including the brain, may 
remain stationary or nearly so in one individual at a period when 
in the great majority they are growing. In the case of the brain 
there may be no arrest apparent in gross structure, and yet the 
neurones themselves may not have attained their full develop- 
ment in complexity and delicacy. If we knew fully the history of 
the growth (normal or pathological) of the neurones themselves, 
we could probably extend the conception of arrested development 
to the entire field of mental life and distinguish in post-mortem 
examinations between the clodhopper who stagnates mentally after 
a score of years, and the Gladstone or Virchow whom the allotted 
span of life leaves still progressing, as we now distinguish be- 
tween the brains of an amaurotic idiot and an average boy. It 
seems, therefore, justifiable to use the phrase ' arrested develop- 
ment ' from the psychological point of view in the case of any 
mental trait in any individual which remains stationary or nearly 
so at a period when it ordinarily is advancing. Medical men com- 
monly apply the phrase to only those well-marked cases of general 
mental weakness which are correlated with gross developmental 
defects of the body or brain. 

Arrest may be temporary or permanent. In the former case 
sickness, low nutrition and disuse are the probable causes ; in the 
latter, definite brain lesions or original lack of developmental 
force. It may be general or specialized. In every trait perma- 
nent arrest comes sooner or later to almost all of us. The dif- 
ferences amongst men are not in its presence or absence, but in 
its date. There is, of course, no absolute date for any trait 
which is ' normal ' for it. The date is variable, and abnormality 
here as elsewhere can mean only some arbitrarily chosen difference 
from the average. 



APPENDIX I 

List of Authors and Titles Referred to Specifically in the Text 

Betts, G. H '09, The Distribution and Functions of 

Mental Imagery, Columbia Univer- 
sity Contributions to Education, 
Teachers College Series, No. 26. 

Binet, A '97, Psychologic individuelle: La des- 
cription d'un objet, L'annee psy- 
chologique, vol. 3, pp. 296-332, 
and. La description d'une cigarette, 
Revue de Psychiatric, 1897, pp. 
235-243- 

Binet, A., and Simon, Th '09, L' intelligence des imbeciles, L'annde 

psychologique, vol. 15, pp. 1-147. 

Brown, W '09, Some Experimental Results in 

Correlation. 

Bruner, F. G '08, The Hearing of Primitive Peoples, 

Archives of Psychology, No. 11. 

Burris, W. P '03, The Correlations of the Abilities In- 
volved in Secondary School Work, 
Columbia Contributions to Phil., 
Psy. and Ed., vol. 11, No. 2, pp. 
16-28. 

Burt, C '09, Experimental Tests of General In- 
telligence, British Journal of Psy- 
chology, vol. 3, pp. 94-177- 

Cattell, J. McK '03, A Statistical Study of Eminent Men, 

Popular Science Monthly, vol. 62, 
PP- 359-377- 
06, A Statistical Study of American 
Men of Science, III. The Distri- 
bution of American Men of Science, 
Science, Dec. 7, 1906. 

Cornman, O. P '02, Spelling in the Elementary School; 

An Experimental and Statistical 
Investigation. 

(23O 



232 Educational Psychology 

Courtis, S. A '09, Measurement of Growth and Effi- 
ciency in Arithmetic, Elementary 
School Teacher, vol. 10, pp. 58- 
74. 177-199- 

Davenport, C. B '10, Eugenics. 

De Candolle, A '73, (Second edition, '85), Histoire des 

sciences et des savants depuis deux 
si^cles, etc. 

Earle, E. L '03, The Inheritance of the Ability to 

Learn to Spell, Columbia Contri- 
butions to Phil., Psy. and Ed., 
vol. II, No. 2, pp. 41-44. 

Ellis, H '94, '04, (Fourth edition, '04), Man and 

Woman. 

'04, A Study of British Genius. 

Fay, E. A '98, Marriages of the Deaf in A merica. 

Galton, F '69, '92, Hereditary Genius: An Inquiry 

into its Laws and Consequences, 
(first edition '69, second edition 
'92). References are to second 
edition. 

'83, Inquiries into Human Faculty and 
its Development. 

'87, Supplementary Notes on Prehen- 
sion in Idiots, Mind, vol. 12, pp. 
79-82. 

'89, Natural Inheritance. 
Gilbert.rj. A '94, Researches on the Mental and Phy- 
sical Development of School-Child- 
ren; Studies from the Yale Psy- 
chological Laboratory, vol. 2, pp. 
40-100. 
Heymans, G., and Wiersma, E., '06 (a), Beitrdge zur speziellen Psychologic 

auf Grund einer Massenuntersuch- 
ung, Zeitschrift iiir Psychologic, 
vol. 42, pp. 81-127, 258-301. 
'06 (b), Beitrdge zur speziellen Psychologic 
auf Grund einer Massenuntersuch- 
ung, Zeitschrift ftir Psychologic, 
vol. 43, pp. 321-373- 

'07, Beitrdge zur speziellen Psychologic 
auf Grund einer Massenuntersuch- 
ung, Zeitschrift ftir Psychologic, 
vol. 45, pp. 1-42. 

'08, Beitrdge zur speziellen Psychologic 
auf Grund einer Massenuntersuch- 
ung, Zeitschrift fiir Psychologic, 
vol. 46, pp. 321-333. 



Authors and Titles 233 

Jacobs, J '87, Experiments on Prehension, Mind , 

vol. 12, pp. 75-79- 

Jacoby, P '81, (Second edition, '04), Etudes sur 

la selection dans ses rapports avec 
I'heredite chez I'homme. 

Johnson, G. E '95, Contribution to the Psychology and 

Pedagogy of Feeble-Minded Child- 
'95, ren, Pedagogical Seminary, vol. 3, 
pp. 246-301. 

Kelly, R. L '03, Psycho-physical Tests of Normal 

and Abnormal Children — A Com- 
parative Study, Psychological Re- 
view, vol. 10, pp. 345-372. 

Krueger, F., and Spearman, C '06, Die Korrelation zwischen verschie- 

denen geistigen Leistungsfdhig- 
keiten, Zeitschrift ftir Psychologic, 
vol. 44, pp. 50-1 14- 

Kuhlmann, F '04, Experimental Studies in Mental 

Deficiency, American Journal of 
Psychology, vol. 15, pp. 391-446. 

Learoyd, M. W '96, The Continued Story, American 

Journal of Psychology, vol. 7, 
pp. 86-90. 

Leclere, A '98, Description d'un objet, L'ann^e psy- 

chologique, vol. 4, pp. 379-389- 

Lobsien, M '03, Einige Untersuchungen iiber das 

Geddchtniss bei Schwachbefdhigten, 
Die Kinderfehler, vol. 8, pp. 157- 
168 and 193-203. 

Loewenfeld, R '03, Uber die Geniale Geistesthdtigkeit 

Meumann, E '07, Vorlesungen zur Einfiihrung in die 

Experimentelle Pddagogik und ihre 
psychologischen Grundlagen. 

Norsworthy, N '06, The Psychology of Mentally De- 
ficient Children, Archives of Psy- 
chology, No. 1 . 

Odin, A '95, Genkse des grands hommes, gens de 

letires fran(ais modernes. 

Pearson, K '04, On tlie Laws of Inheritance in Man, 

II. On the Inheritance of the Men- 
tal and Moral Characters in Man, 
etc., Biometrika, vol. 3, Part II, 
pp. 131-190. 



234 Educational Psychology 

Pearson, K '07, On the Relationship of Intelligence 

to Size and Shape of Head, and to 
Other Physical and Mental Char- 
acters, Biometrika, vol. 5, pp. 105- 
146. 

Pedersen, R. H '05, Experimentelle Untersuchungen der 

visuellen und akustischen Er in- 
ner ungshilder, angestellt an Schul- 
kindern, Archiv fur die gesamte 
Psychologic, vol. 4, pp. 520-534. 

Rice, J. M '97, The Futility of the Spelling Grind, 

The Forum, vol. 23, pp. 163-172 
and 409-419. 

'02, Educational Research: A Test in 
Arithmetic, The Forum, vol. 34, 
pp. 281-297; Causes of Success 
and Failure in Arithmetic, The 
Forum, vol. 34, pp. 437-452. 

'03, Educational Research, The Results 
of a Test in Language, The Forum, 
vol. 35, pp. 269-293. 

'04, English, Tlie Need of a New Basis 
in Education, The Forum, vol. 
35, PP- 440-457- 

Richardson, H '02, The Etiology of Arrested Mental 

Development, Journal of Psycho- 
Asthenics, vol. 7, pp. 9-14. 

Segal, J '08, ijber den Reproduktionstypus und 

das Reproduzieren von Vorstel- 
lungen, Archiv fur die gesamte 
Psychologic, vol. 12, pp. 124-235. 

Simon, Th '09, (See Binet and Simon.) 

Spearman, C '04 (a). The Proof and Measurement of 

Association between Two Things, 
American Journal of Psychology, 
vol. 15, pp. 72-101. 
'04 (b), "General Intelligence" Objectively 
Determined and Measured, Amer- 
ican Journal of Psychology, vol. 
15, pp. 201-292. 

" (with F. Krueger), '06, Die Korrelation zwischen verschie- 

denen geistigen Leistungsfdhigkeii- 
en, Zeitschrift f{ir Psychologic, vol. 

44, PP- 50-114- 

Stern, L. W '00, Uber Psychologie der individuellen 

Differemen. 



Authors and Titles 



235 



Stone, C. W '08, Arithmetical Abilities and Some 

Factors Determining Them, Colum- 
bia University Contributions to 
Education, Teachers College Series, 
No. 19. 

Thompson, H. B '03, Psychological Norms in Men and 

Women, University of Chicago 
Contributions to Philosophy, vol. 

4, No. I. 

Thorndike, E. L '03, Heredity, Correlation and Sex Dif- 
ferences in School Abilities, Colum- 
bia University Contributions to 
Phil., Psy., and Ed., vol. 11, No. 2. 
'04, An Introduction to the Theory of 
Mental and Social Measurements. 
'05, Measurements of Twins, Archives 
of Philosophy, Psychology, and 
Scientific Methods, No. i. 
'08, Alemory for Paired Associates, 
Psychological Review, vol. 15, 
pp. 122-138. 
'09, The Relation of Accuracy in Sen- 
sory Discrimination to General In- 
telligence, American Journal of 
Psychology, vol. 20, pp. 364-369. 
10, Handwriting, Teachers College 
Record, vol. 11, No. 2. 

Ward, L. F '06, Applied Sociology. 

Wiersma, E (See Heymans and Wiersma.) 

Wissler, C '01, The Correlation of Mental and 

Physical Tests, Psychological Re- 
vievF Monograph Supplement No. 
16, June, 1 90 1. 
'03, The Growth of Boys, American 
Anthropologist, New Series, vol. 

5, pp. 81-88. 

Woods, F. A '06, Mental and Moral Heredity in 

Royalty. 

Woodworth, R. S '10, Racial Differences in Mental Traits, 

Science, New Series, vol. 31, pp. 
171-186. 

Wylie, A. R. T '00, Taste and Reaction Time of the 

Feeble-Minded, Journal of Psycho- 
Asthenics, vol. 4, No. 3; A Study 
of the Senses of the Feeble-Minded, 
ibid., vol. 4, No. 4; Memory of the 
Feeble-Minded, ibid., vol 5, No. i ; 
Motor Ability and Control of the 
Feeble-Minded, ibid., vol. 5, No. 2. 



APPENDIX II 

List and Descriptions of Measurements Referred to Cursorily in the 

Text 

A Test: Marking A 's. 

A sheet printed with capital letters, as shown below, is used. The 
individual who is being measured is instructed ' to mark as many A's 
as he can,' or 'to mark as many and omit as few A's as he can,' or 
'to mark all the A's.' The score used is the number marked in a given 
time (or the time required for the entire sheet to be gone over) and 
the number of omissions. 

OYKFIUDBHTAGDAACDIXAMRPAGQZTAACVAOWLYX 

WABBTHJJANEEFAAMEAACBSVSKALLPHANRNPKAZF 

YRQAQEAXJUDFOIMWZSAUCGVAOABMAYDYAAZJDAL 

JACINEVBGAOFHARPVEJCTQZAPJLEIQWNAHRBUIAS 

SNZMWAAAWHACAXHXQAXTDPUTYGSKGRKVLGKIM 

FUOFAAKYFGTMBLYZIJAAVAUAACXDTVDACJSIUFMO 

TXWAMQEAKHAOPXZWCAIRBRZNSOQAQLMDGUSGB 

AKNAAPIvPAAAHYOAEKLNVFARJAEHNPWIBAYAQRK 

UPDSHAAQGGHTAMZAQGMTPNURQNXIJEOWYCREJD 

UOLJCCAKSZAUAFERFAWAFZAWXBAAAVHAMBATAD 

KVSTVNAPLIIvAOXYSJUOVYIVPAAPSDNLKRQAAOJLE 

GAAQYEMPAZNTIBXGAIMRUSAWZAZWXAMXBDXAJZ 

ECNABAHGDVSVFTCIvAYKUKCWAFRWHTQYAFAAAOH 

a — t Test: Marking U^ords Containing, Each, Both a and t. 

A sheet printed with text, as shown below, is used. The individual who 
is being measured is instructed, and the score is kept, as in the A test. 
The same sheet is used for marking words containing other combina- 
tions of letters, such as r and e, or i and /. 

A. 

Dire tengo antipatia senores; esto seria necedad, porque hombre vale 
siempre tanto corao otro hombre. Todas clases hombres merito; 
resumidas cuentas, sulpa suya vizconde; pero dire sobrina puede 
contar dote veinte cinco duros menos, tengo apartado ; pardiez tamado 

(236) 



Descriptions of Measurements 237 

trabajo atesorar-los para enriquecer estrano. Vizconde rico. Mios, 
quiero ganado sudor f rente saiga familia; suyo, pertenence, tendran. 
Conozco marido pueda convenirle Isabel: Carlos, sobrino. Donde 
muchacho honrado, mejor indole, juicioso, valiente? Quieres sobrino. 
Esposo parece natural, pero. Pero, pero, diablos objeciones hacer. 
Posible quedandonow solos siempre hacer oposicion. Solo delante 
hentes eres ministerial. Pues, sidens siempre plan, dicho antes, porque 
hace tierapo notade cose aflige cierto. Sabes cuante quiero Carlos; 
consuelo apoyo; despues persona quiero mundo. Como eres buena 
amable, quieres porque, darme gusto, pero quisiera. Palabra cuesta 
trabajo; parece sino teines miedo agasajarle, manifestarle carino. 
Veces tratas cumplimiento veces senor. Probare; ejemplo pudiendo 
abandonar case negocios, deseaba hubiese acompanado viaje; pre- 
feriste sola sobrina doncella. Quise contradecir, pero para sen- 
timiento, para tambien. Voto gasta palabra, dice frases, dice; pero 
alia adentros quiere. Mientras estado malo, puesto dirigir casa; 
pardiez aunque carrera, hacia mejor; cabo tiene sobre ventaja poca 
edad, actividad zelo, pues para contigo digo. Siempre ordenes; dejaria 
matar alcanzarte billete para opera para baile . Necsitamos para felices ; 
algo estrano, desconocido. Esta resuelto; supuesto hemos hablado 
esto, mismo preciso empieces darle conocer nuestros planes. Quien 
mejor. Opone nunca deseos, sera facil nadie persuadirle. Probare 
menos, preciso sino creere tienes interes decidido proteger vizconde. 
Pudieras creer siempre inclinado senores cabra tira monte. Pero tengo 
nada ellos esposo tienes siempre pensativo siempre trists. Diablos 
tiene Carlos acercate, tiene hablarte. Hola parece sacado letargo tengo 
algunas instrucciones cajero marcha dentro poco. Para empresa piesna 
usted establecer Habana. Precisamente bonita especulacion bien 
manejada sobro todo. Espero pero tengo entre manos etro proyecto 
interesa aqui estabamos ocupando pienso. Eres porque quieres 

B. 
porque e tregas defensa peligro lugar huir mujer, harto debil duda pero 
algun desgracia tuviese luchar sentimientos semejantes tuyos, lejos 
ceder ellos cobardemente moriria pero triunfaria. Tendras menos 
valor tendre darte lecciones valor energia. Vamos, Carlos, amigo 
creeme sentimiento, profundo razon pueda subyugar, desgracia grande 
pueda soportar veneer nuestro corazon. Ofrezco apoyo eres creo sequiras 
consejos. Bien, hable usted. Quiere casarte Isabel. Isabel, prima 
imposible; quiere otro, vizconde amigo. Preciso persuadirselo hare 
otros partidos habra jamas para jurado nada espero pero conservare 
siempre entero este amor ella ignora unos juramentos recibido. En- 
horabuena otro medio asequarara tranquilidad, uya destino ofrecido 
aleja Madrid, preciso aceptarle. Privarme presencia felicidad hecho 
usted para consejo especie embargo preciso seguirle solo puedes con- 
servar amistad elige. Jamas caballero crei usted digno consejos dejo 
usted abandonado mismo nada tango decirle Carlos aleja, echa mirade 
salir Dona mira; suspira sale. Porque inquieta partida desterremos 
para siempre memoria quiero puedo presente terao; ausente, echo 



238 Rducational Psychology 

menos, verle sonrojo, nombre hace temblar. Embargo nunca dicho 
debiera ignorarlo Dios Dame fuerzas para resistir. 

Alphabet Test. 

A sheet printed with/, k, s, p, u, I, e, r, d, 0, v, j, n, t and h in a cokimn 
is used. Instructions are: — 'to write after each letter, the letter that 
comes immediately before it in the alphabet.' The score records 
time required (or number written in a given time), errors and omissions. 

Genus-Species Test. 

A sheet printed with hook, tree, room, toy, name, dish, boat, game, plant 
and Jish in a column is used. Instructions are: — 'to write, after each 
word, a word which means some kind of the thing named by the printed 
word.' The score is kept as in the Alphabet test. The words may 
be given to the subject, and the replies made by him orally. A harder 
list is used for older children. 

Geometrical Forms Test: Marking Circles, Hexagons, etc. 

A sheet printed with Fig. 71 is used. Instructions and scoring are as 
in the A or a — t test. 

Maze Tests. Drawing a Line between Two Given Lines. 

Sheets printed with Fig. 72, or similar mazes, are used. The instructions 
are to draw a line along the pathway as quickly as possible without 
touching the sides. The score includes amount done (or time taken), 
and number of touches. 

Memory of Related Words. 

Memory of such series as: — school, teacher, book, desk, pen, read, write, 
add, spell, word. 

Memory of Unrelated Words. 

Memory of such series as: — red, dog, buy, day, never, sing, boy, sick, tree, 
can. 

Misspelled Word Test: Marking Misspelled Words. 

Sheets printed with passages like that below are used. Instructions and 
scoring are as in the A test. 

1. On the 3d of September, 1832, inlcligence was broght to the collecter 
of Tinnevelly that soni wildd eliphants had appeared in the neighbor- 
hod. A hunting party was imediately formed, and a large number of 
nattive hunters were engaged. We left the tents, on horsback, at 
half-past sevin o'clock in the morrning and rode thre miles to an open 
spote, Hanked on one sid bye Rice-fields, and on the other by a jungle. 

2. After waiting som time, Captain B and myself walked acros the 

rice-fields to the shad of a tree. There we herd the trunipett of an 
elephant; we reshed acros the rice-fields up to our knes in mud, but 
all in vain, thogh we came upon the trak of one of the animels, and 
then ran five or six hundredd yards iutoo the jungle. 



Descriptions of Measurements 



239 






on 



mh 



n 



D' 



r\^' 



<]vgAoa^i:^ 

o 







pRny anySHMn^Poo 



iRo^p°^° 



O 



< 



1^7 




H<\a 






<^ 



n<i0o 



LJ>iA^nC 



e3HRB 



DPsOQ 



ooDdD[5d dooc 






D 



oC^ 



240 



Educational Psychology 




Descriptions of Measurements 241 

3. After varius false allarms, aud vane endevors to discuvor the obgects 

of our chace, the colector went into the jungle, and Captin B 

and myself into bed of the stream' where we had sen the traks; and 
here it was evedent the elaphents had passed to and fro. Disapointed 
and impasient, we allmost determined to giv up the chace and go 
home; but shots fird just before us reanimated us, aud we proceded, 
and found the collecter had just firred twicce. 

4. Of we went throuh foerst, over ravin, and through strems, till att 
last, at the top of the ravine, the elephants were seen. This was a 
momant of excitment! We wer all scatered. The collector had 

taken the midle path ; Captain B , some huntsmen, and myself 

took to the feft; and the other hunters scrabled down that to the 
rite. At this momunt I did not see enything but after advanceing a 
few yards, the hugh hed ef an elephunt shaking abuve the jungle, 
withen ten yards of us, burst sudenly upon my view. 

5. Captain B ande a hunter justt befor me: we al fired at the 

same moment, and in so dirrect a line thet the percussion cap of my 
gun hitt the hunter, whome I thougt at first I had shoot. This accident, 
thogh it pruved slight, troubled me a litle. The grate excitement 
ocasioned by seeing, for the first tim, a wild best at liberty and in a 
state of natur, product a sensation of hop and fear that was intens. 

Opposites Tests. 

Sheets printed with words in a column are used, one list being: — good, 
outside, quick, tall, big, loud, white, light, happy, false, like, rich, sick, 
glad, thin, empty, war, many, above and friend. Another list is: — bad, 
inside, slow, short, little, soft, black, dark, sod, true, dislike, poor, well 
sorry, thick, full, peace, few, below and enemy. 

Harder lists, used for older children and adults, are:— serious, grand, 
clumsy, to win, to respect, frequently, apart, stormy, motion, forcible, 
to float, straight, to hold, after, unless, rough, to bless, to take; and bar- 
barous, simple, rude, obscure, gentle, to expand, elation, adroit, loquacious, 
to degrade, to hinder, precise, permanent, repulsion, to respect, genuine, 
separate, deceitful. 

Instructions are to write (or, if the test is given orally, to say) the word 
which means the opposite of the given word, 'just what that word 
does not mean.' The score is kept as in the Alphabet test. 

Part-Whole Test. 

To give the name of that whole thing of which the printed or spoken 
word is a part. The list used for young children and for mentally 
deficient individuals is: — door, pillow, letter, leaf, button, nose, cover 
page, engine, and glass. 

Word Test. 

To write words conforming to certain requirements, such as: — 'to contain 
six letters,' or 'to contain a and g.' 
16 



APPENDIX III 

List and Definitions of Statistical Terms 

Measures of Central Tendency. 

The Average = (the sum of the individual measures) -=- (their number). 
The Median = the middle measure, the measure so chosen that the 
number of measures greater than it equals the number less than it. 
The Mode = the most frequent of the individual measures. 

Measures of Variability. 

The Average Deviation (A. D. dis.) = the average of the deviations 

(regardless of signs) of the individual measures from their central 

tendency. 
The Median Deviation (P. E. dis.) or Probable Error (when used as a 

measure of variability) = the median of the deviations (regardless 

of signs) of the individual measures from their central tendency. 
The Mean Square Deviation (S. D. dis.) = the square root of the average 

of the squares of the deviations of the individual measures from their 

central tendency. 

Measures of Reliability. 

The average deviation of the true central tendency from that obtained 

A D dis 
from a random selection of n measures (A. D. ^j_ ^^ q x^~ ~ — " 

l/n 
Similarly, 

P P _ P. E. dis. ^, ^ J. S. D. dis. 

P-E- tr.-ob.C.T.= 7=- and S. D. j^_^^ (,^ = 

yn V ^ 

For measures of the reliability of measures of variability and of relations 
see Thorndike, Mental and Social Measurements, Chapter X. 

Measures of Relations. 

Let xi, X2, X3, X4, etc., be the first series of divergences. 
Let yi, y2, ys, yi, " " " second " " 

Let ^ x.y be the sum of the products xiyi, X2y2, xsya, X4y4, etc. 
Let i' x2 " " " " " squares xi^, x^, x^, Xi\ etc. 
Let y y2 " " " " " " yi2, y22, y^, yi\ etc. 

I x.y 

Then the Pearson Coefficient of Correlation, R, = 

For other measures of relations see the author's Mental and Social 
Measurements, Chapter IX, and Empirical Studies in the Theory of 
Measurement, §§ 5 to 9, inclusive. 

(242) 



INDEX OF NAMES 



Barr, M. W., 102. 
Betts, G. H., 183, 195. 
Binet, A., 203, 215. 
Brown, W., 182. 
Bruner, F. G., 56, 57- 
Burris, W. P., 96. 
Burt, C, 181, 182, 184. 

Cattell, J. McK., 35 f., 119, 121 ff., 184. 
Cole, L. W., 40. 
Cornman, O. P., 78, 135. 
Courtis, S. A., 135. 

Davenport, C. B., 102. 
DeCandolle, A., 121. 



McDougall, W., 56, 57- 
Mayo, M. J., 52 ff. 
Mendel, G., 98. 
Meumann, E., 183, 194, 201. 

Norsworthy, N., 215, 217, 221. 

Odin, A., 121. 

Pearson, K., 43 f., 80, 81, 82, 83, 84, 

96, 182, 224. 
Pedersen, R. H., 183. 

Ranke, J., 55. 

Rice, J. M., 78, 119, 125 ff. 

Richardson, H., 103. 



Earle, E. L., 40, T] f. 

Ellis, H., 36. 49 f.. 61 ff., 94 f., 121, ^'^"'■'' ^- ^- ^•' 56. 59. 

225 ff. C 1 T 

Segal, J., 194. 

Seguin, E., 218. 

Simon, Th., 215. 

Simpson, B. R., 182. 
Galton, P., 65 f., 70, 78, 79, 93, 94, Sollier, P., 219. 

119 ff., 121, 215. Spearman, C, 80, 182, 185, 188. 

Gilbert, J. A., 30 f., 40, 105 ff-, Ii3- Stern, L. W., 201 ff. 

Stone, C. W., 135. 
Heymans, G., 45, 46, 48, 9'2; 93 Strayer, G. D., 42. 



Fay, E. A., TJ. 
Fox, W. A., 40. 



Jacobs, J., 215. 
Jacoby, P., 121. 
Johnson, G. E., 215. 

Kelly, R. L., 215. 
Kraepelin, E., 204. 
Kuhlmann, F., 215. 

Learoyd, M. W., 5°. 
Leclere, A., 203. 
Lobsien, M., 215. 
Loewenfeld, R., 79, 227. 



Thompson, H. B., 20 ff., 32, 37, 42. 
Thorndike, E. L., 89, 96, I3S, 165, 
182, 184. 

Ward, L. F., 121. 
Wiersma, E., 45, 46, 48, 92, 93. 
Wissler, C, 30, 43. 182, 188. 
Woods, F. A., 84 ff., 124, 224. 
Woodworth, R. S., 55 ff- 
Wylie, A. R. T., 215. 



(243) 



INDEX OF SUBJECTS 



Ability, inheritance of, 80 flf. 

Abnormal. See Exceptional. 

Achievement, relative versus absolute, 
138 ff. 

Activities, sex differences in, 46 ff. 

Addition, individual differences in, 
144 f. 

Age, changes in mental traits with, 
105 ff. 

Ancestry. See Inheritance. 

Arithmetic, differences of school 
classes in, 129; the causes of ability 
in, 129, 131 ff. 

Arrested development, 228 ff. 

Artistic faculty, inheritance of, 80. 

Assertiveness, inheritance of, 80 ff. ; 
sex differences in, 44 f. 

Association, sex differences in, 30 f. ; 
the inferiority of intellectually defi- 
cient individuals in, 218; the in- 
heritance of speed and control in, 
89 ff. 

Athleticism, inheritance of, 83 ; sex 
differences in, 44 f. 

Attenuation of resemblances, 80 f. 

Average Deviation. 13 f. See also 
Measurement. 

Averages. See Measurement. 

Brightness. See Senses. 
British genius, racial differences in, 
61 ff. 

Central Tendency, 12. 
Cephalic index, inheritance of, 72, 76. 
Chance form of distribution, 160 ff. 
Character, sex differences in, 44 ff. ; 
types of, 193 ff. 



Characters, unit and multiple, 98 ff. 

Classification, of individuals, 142-206 
passim; of individuals exceptionally 
inferior in intellect, 213 f. ; of in- 
dividuals exceptionally inferior in 
morals, 223 f. 

Color. See Senses. 

Combinations of traits, 3 f., 193 ff. 

Compensations in mental relations, 
183 ff. 

Conscientiousness, inheritance of, 
80 ff. ; sex differences in, 44 f. 

Continuity of variations, 149 f. 

Correlations See Relations. 

Curve of frequency, 16. See also Dis- 
tribution and Distributions. 

Dealing, relations of ability in, 181 f. 
Defectives. See Exceptional. 
Determiners of traits in the adult, 

97 ff. 

Deviations. See Individual Differ- 
ences, Distributions, Distribution of 
Amounts of a Trait, and Varia- 
bility. 

Dilation of resemblances by variations 
in the scales used, 81 f., 83. 

Discrimination. See Sensory Dis- 
crimination and Senses. 

Distribution of amounts of mental 
traits, IS f., 142 ff. ; as affected by 
mixture of species, 166; as affected 
by selection, 167 ff. ; as affected by 
the number of cases, 159; multi- 
modality of, 152 ff. ; the probability 
type of, 160 ff. See also Individual 
Differences and Variability. 

Distributions, corresponding to stated 



(244) 



Index of Subjects 



245 



group differences, 28 f., 33, 64, 
66; of adult women, in add- 
ing, 144 f., 150, in discrimination of 
length, 144, in memory of digits, 
151 ; of boys, in giving opposites, 
151, in marking A's, 151, in mark- 
ing words containing a and /, 151 ; 
of boys and girls, in age at reach- 
ing a given grade, 42, 158, in mark- 
ing A's, 154 f. ; of individuals, in 
combinations of traits, 194 ff. ; of 
men, in reaction-time, 151 ; of men 
and women, in ingenuity, 23, 25 ; of 
relationships, 174 ff. ; of whites and 
Negritos, in the block test, 61, 156; 
of whites and negroes, in scholar- 
ship, 54 f., 157. 

Economics, sex differences in scholar- 
ship in, 31. 

Emotions, sex differences in, 44 ff. 

English, sex differences in scholar- 
ship in, 31. 

Environment, and maturity, the co- 
operation of, 109 f. ; and original 
nature, the cooperation of, 138 ff. ; 
as a cause of multimodality or dis- 
tinct types, 153 f., 154 f. ; as a cause 
of sex differences, 38, 42; differ- 
ences in as causes of individual 
differences in ability in arithmetic, 
129, 131 ff., in ability in spelling, 
• 126 ff., in scientific achievement, 
122 f., in the choice of a profession, 
134 f. ; is, in part, selected by an 
individual's nature, 117; resem- 
blances in, as causes of individual 
resemblances in ability to learn to 
spell, 78, in genius, 79, in various 
mental traits, 83-93 passim; the 
action of is differential, 116 f . ; the 
influence of in the case of twins, 
119 ff. 

Exceptional inferiority, 211 ff. ; in 
intellect, 213 ff. ; in morals, 223 f. 

Exceptionally defective individuals 
intellectually, 213 ff. ; classification 



of, 213 f. ; general description of, 
219 f. ; measurements of, 215 ff., 
221 f. ; relative inferiority of in dif- 
ferent traits, 216 f. ; symptoms of, 
214; treatment of, 214 f. 

Exceptional rates of growth, 224 ff. ; 
rapid growth, 225 ff. ; slow growth, 
228 f. 

Exceptional superiority, 209 f. 

Extreme individual differences, 207 ff. 

Eye-color, inheritance of, 76. 

Fallacy of unfair selection, 112, 114 f. 

Family. See Inheritance. 

Fatigue, age differences in, 105 ff. ; 
sex differences in, 27. 

Feeble-mindedness. See Exception- 
ally Defective Individuals. 

Frequency. See Distribution, Dis- 
tributions, and Variability. 

Genius, inheritance of, 78 f. ; racial 
differences in, 61 ff. ; sex differ- 
ences in, 35 f. 

Groups, measurement of differences 
between, 24 ff., 37 ff. 

Growth. See Maturity. 

Habits, effect of on relations, 191 f. ; 
formation of in individuals excep- 
tionally defective in intellect, 214 f.; 
indifference of certain habits to all 
natures, 137 f. ; not measures of 
capacity, 67 ; relation to multimodal- 
ity, 153 f. ; susceptibility of to 
environmental influence, 141. 

Hair-color, inheritance of, 77. 

Handwriting, inheritance of, 80 ff. ; 
sex differences in, 44 f. 

Heredity. See Inheritance. 

History, sex differences in scholar- 
ship in, 31. 

Idiocy. See Exceptionally Defective 

Individuals. 
Illusions, sex differences in, 30 f. 



246 



Educational Psychology 



Imagery, individual differences in, 

193 ff. 

Imbecility, and Mendelian inherit- 
ance, 102 f. See also Exceptionally 
Defective Individuals. 

Immaturity, tests of, 229. 

Individual differences, environment as 
a cause of, 114 ff. ; extreme, 207 ff. ; 
immediate ancestry as a cause of, 
6g ff. ; in combinations of traits, 
193 ff. ; in single traits, 142 ff. ; 
maturity as a cause of, 104 ff. ; 
measurement of, 3 ff. ; remote 
ancestry as a cause of, 51 ff. ; sex 
as a cause of, 18 ff. 

Information, sex differences in 
amount of, 28. 

Ingenuity, sex differences in, 28. 

Inheritance, analysis of, 97 ff. ; and 
education, 138 ff. ; and responsibil- 
ity, 140; blended versus Mendelian, 
99 ff. ; from near ancestry, 69 ff. ; 
from remote ancestry, 51 ff. ; Men- 
delian, 98 ff. ; of ability, 80 ff. ; of 
ability to learn to spell, yy i. ; of 
artistic faculty, 80; of assertiveness, 
80 ff. ; of athletic ability, 83; of 
cephalic index, 72, 76; of conscien- 
tiousness, 80 ff. ; of deafness, yy ; 
of eye-color, 76 ; of genius, 78 f. ; 
of hair-color, yy; of handwrriting, 
80 ff. ; of imbecility, 102 f. ; of in- 
tellect, 84 ff. ; of morals, 84 ff. ; of 
popularity, 80 ff. ; of self-conscious- 
ness, 80 ff . ; of stature, y6 ; of tem- 
per, 80 ff. ; of vivacity, 80 ff. ; 
specialization of, 93 ff. 

Instincts, sex differences in, 48 f. 

Intellect, defects of, 207 ff. ; inherit- 
ance of, 78, 80 ff. ; racial differences 
in, 58 ff. ; sex differences in, 44 ff. ; 
types of, 193 ff. 

Interests, sex differences in, 46 ff. 

Inverse correlations, 200. 

Languages, sex differences in scholar- 
ship in, 31. 



Mathematics, sex differences in 
scholarship in, 31. 

Maturity, and environment, the co- 
operation of, 109 f. ; exceptional 
individuals in the rate of 224 ff. ; 
the influence of upon individual 
mental differences, 104 ff. ; the in- 
fluence of upon multimodality, 155; 
the measurement of the influence 
of, 104, iioff. 

Measurement, of changes with age, 
1 10 ff. ; of group differences in 
amount, 24 ff. ; of group differences 
in variability, 27 ff- J of individual 
differences, 3 ff. ; of mental rela- 
tions, 172 ff. ; of relative inferiority 
in different traits, 216 f. ; of resem- 
blance, 71 ff. ; of variability, 15 ff. 

Measurements. See the references 
given under the subject concerned. 

Median, 13. 

Median ratio, 74. 

Memory, in individuals exceptionally 
deficient in intellect, 219, 221 f. ; of 
digits, distribution of, 151; relations 
of, 182 ; sex differences in, 28, 30 f. 

Mental science, sex differences in 
scholarship in. 31. 

Mode, 12. 

Moral traits, exceptional inferiority in, 
223 f. ; inheritance of, 80 ff., 86 ff., 
92 f. ; sex differences in, 44 ff. 

Motor ability, differences in, due to 
age, 105 ff. ; differences in, due to 
sex, 2y, 30 f. ; in individuals excep- 
tionally deficient in intellect, 218 f., 
221 f. 

Multimodality, 152 ff. 

Multiple type theory, 152 ff., 195 ff. 



Negritos, ability of in matching 
forms, 60 f. 

Negroes, and whites compared in 
scholarship, 52 ff. ; intellectual 
powers of, according to Galton, O5 f. 

Nurture. See Environment. 



Index of Subjects 



247 



Objective measurements, 5 f. 
Opposition of traits. See Relations, 
inverse. 

Pain. See Senses. 

Pearson coefficient of correlation, 
74 fif., 180 f. 

Perception, distribution of individuals 
in, 151 ; inheritance of ability in, 
89 ff. ; racial differences in, 58; sex 
differences in, 27, 30 f., 41 ; special- 
ized in inheritance, 97 f. 

Pitch. See Senses. 

Popularity, inheritance of, 80 ff. ; sex 
differences in, 44 f. 

Precocity, 225 f. 

Pressure. See Senses. 

Primitive races, mental traits of 55 ff. 

Probability form of distribution, 160 ff. 

Profession, causes of an individual's 
choice of a, 134 f. 

Qualitative differences, reducible to 
quantitative, 4. 

Race, as a cause of individual differ- 
ences, 51 ff. ; as a cause of multi- 
modality, 154 f. 

Races, the interpretation of the dif- 
ferences of, in achievement, 64 ff. 

Range of sensitivitjf. See Senses. 

Rates of growth, exceptional, 224 ff. 

Reaction time, age differences in, 
IDS ff. ; distribution of ability in, 
151 ; sex differences in, 27, 30 f. 

Relations between amounts of differ- 
ent traits in the same individual, 
171 ff. ; common factor in, 185 f . ; 
comparison of, 179 f . ; curvilinear, 
178 f. ; general features of, 189 ff. ; 
inverse, 183 ff., 200; measurement 
of, 172 ff. ; rectilinear, 177 ff. ; signi- 
ficance of, 183 ff. ; through identity 
of form, 186 ff. ; variability of, 
174 ff. See also Resemblances. 

Reliability of mental measurements, 
II ff. 



Resemblances, attenuation of, 80 f. ; 

dilation of, 81 f., 83 ; measurement 

of, 71 ff. 
Royal families, hereditary resemblance 

in, 84 ff. 

Scales, for mental traits, 5 ff. 
Scholarship, of whites and negroes 
compared, 52 ff., sex differences in, 

31- 

School progress, sex difference in 
variability in, 41 f. 

School work, individuals failing in, 
220 f. 

Science, the causes of achievement in, 
122 ff. 

Selection, fallacies due to unfair, 112, 
114 f . ; influence of on the form of 
distribution, 167 ff. 

Selective thinking, inferiority of in- 
tellectually deficient individuals in, 
218, 222 f. ; sex differences in, 31. 

Self-consciousness, inheritance of, 
80 ff. ; sex differences in, 44 f. 

Senses, age differences in the, 105 ff. ; 
racial differences in the, 55 ff. ; sex 
differences in the, 27 ff. 

Sensory discrimination, individual dif- 
ferences in, 144 f., 151 ; inferiority 
of intellectually deficient individuals 
in, 218 f. ; relations of, 181 f. See 
also Senses. 

Sex, as a cause of individual differ- 
ences, 18 ff. ; as a cause of multi- 
modality, 154. 

Sex differences, 18 ff. ; in abilities, 
20 ff. ; in character and interests, 
43 ff. ; in variability, 34 ff. 

Sexes, differences in the training of 
the, 18, 32. 

Shyness, sex differences in, 44 f. ; 
the inheritance of, 80 ff. 

Simple and compound differences, 3 f. 

Single type theory, 145, 168 ff., 195 ff. 

Skewness of distribution, 167 ff. 

Slow growth, 228 ff. 

Sorting, relations of abilities in, 181 f. ; 
sex differences in, 27. 



248 



Educational Psychology 



Specialization, of heredity, 93 ff. ; of 
mental traits, 186 flf. 

Speed of mental and motor processes, 
racial differences in, 58. 

Spelling, differences of different 
school classes in, 127 f. ; sex differ- 
ences in, 31 ; the causes of ability 
in, 126 ff. ; the inheritance of the 
ability to learn, yy f. 

Stature, inheritance of, 76; of mental 
defectives, 218. 

Subjectivity, of measures, 5 ff . ; sex 
differences in, 50. 

Suggestibility, differences in due to 
age, 105 ff. 

Surface of frequency. See Distribu- 
tion. 

Tapping, relations of ability in, 181 f. ; 
sex differences in, 27. 

Taste. See Senses. 

Temper, inheritance of, 80 ff. ; sex 
differences in, 44 f. 

Temperament, individual differences 
in, 19s ; sex differences in, 44 ff. 

Temperature, of individuals exception- 
ally inferior in intellect, 221 f. See 
also Senses. 

Tests. See the references under the 
subjects concerned. See also 
Appendix II. 

Threshold. See Senses. 



Touch. See Senses. 

Training. See Environment. 

Twins, resemblances of, 72 ff., 89 ff. ; 
specialization of inheritance in, 
96 ff. ; the action of likenesses and 
differences in the environment upon, 
119 ff. 

Types of intellect and character, 
171 ff., 193 ff. 

Variability, allowance for in the com- 
parison of defects in different traits, 
266 f. ; allowances for in the com- 
parison of relations, 178 ff. ; compari- 
son of groups in respect to, 37 ff. ; 
methods of measuring, 15 ff. ; of 
determiners, loi ; of different 
measures of ostensibly the same 
mental fact, 11 ff. ; of germs from 
the same parents, 71 ; of individuals 
of the same sex and ancestry, 69 ff. ; 
of races, 53 ; of the same groups in 
different traits, 144 ff. ; of the sexes, 
ZZ ff- ," reduction of in individuals of 
similar ancestry, y2. See also 
Individual Differences and Distribu- 
tion. 

Vivacity, inheritance of, 80 ff. ; sex 
differences in, 44 f. 

Weight, of mental defectives, 218. 
Zero-points for mental scales, 146 flF. 



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